Microsoft Windows & Server Evaluation, KMS & Product Keys — The Complete Free Guide (2026)

This is the complete TechyGeeksHome reference for Microsoft Windows and Windows Server product keys. Whether you need evaluation keys to spin up a test lab, KMS client keys (GVLKs) for a volume licensing deployment, dummy keys for SCCM or MDT task sequences, or guidance on how to rearm and extend your evaluation period — it’s all here in one place.

These keys are publicly documented by Microsoft and are not pirated or cracked keys. KMS client keys are published by Microsoft at learn.microsoft.com. Evaluation keys are provided by Microsoft for legitimate testing purposes.

Understanding Key Types: Evaluation vs KMS vs Dummy

Before using any key from this guide, it helps to understand what each type does:

Evaluation keys activate a time-limited trial copy of Windows or Windows Server for 180 days. They are provided by Microsoft specifically for testing and lab environments. After 180 days, the installation will begin showing activation warnings, but you can rearm for additional time (see the rearm section below).

KMS client keys (GVLKs — Generic Volume License Keys) are used in enterprise environments where a KMS (Key Management Services) host server is present on the local network. These keys tell Windows to activate against your KMS host rather than Microsoft’s servers. They are publicly documented by Microsoft and are not activation keys in themselves — they require a valid KMS host to complete activation.

Dummy keys allow Windows to progress through the installation process without activating. This is useful when building MDT or SCCM task sequences where you want to deploy an image without tying it to a specific licence at install time. The system will install successfully but will show as not activated.

Activation Commands Reference

All commands below should be run from an elevated Command Prompt (right-click CMD → Run as administrator).

Apply a product key

slmgr.vbs -ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX

Replace the Xs with your product key. Use this to apply KMS client keys or evaluation keys.

Trigger activation

slmgr.vbs -ato

Check current licence status

slmgr.vbs -dlv

Rearm the evaluation period

slmgr.vbs -rearm

Resets your 180-day evaluation timer. Reboot required. Can be used up to five times.

Convert evaluation to full edition using DISM (Server 2019 and later)

DISM /online /Set-Edition:ServerStandard /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX /AcceptEula

For Datacenter edition, replace ServerStandard with ServerDatacenter. A reboot is required after conversion.

Extending Your Evaluation: Rearm Guide (Up to 360+ Days)

By default, Windows evaluation editions give you 180 days of use. When the evaluation period expires, you can rearm it — resetting the timer for another 180 days. Microsoft allows up to five rearms, which theoretically gives you up to 900 days of evaluation use.

But there is a registry method that extends this even further, potentially giving you up to 360 days from a fresh install.

Standard rearm (up to 5 times)

From an elevated command prompt:

slmgr -rearm

Reboot after running the command. Each rearm resets the 180-day timer. You can rearm up to five times.

Registry method — unlock additional rearms

To unlock additional rearm cycles beyond the standard five, follow these steps:

1. Click Start and type regedit, then press Enter.
2. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform
3. In the right pane, find the value SkipRearm.
4. Double-click it and change the value from 0 to 1.
5. Reboot your machine.

After changing SkipRearm to 1, you can rearm up to a further eight times, giving an additional 240 days. Combined with the initial evaluation period and standard rearms, this can extend your total evaluation time significantly — useful for extended lab testing or training environments.

Note: This method is intended for legitimate evaluation and testing use. Production environments should use properly licensed software.

Windows Server 2025 — Evaluation & KMS Keys

Windows Server 2025 is Microsoft’s current Long-Term Servicing Channel (LTSC) release. Key new features include hotpatching (apply security updates without rebooting), improved Active Directory, enhanced SMB security, and deeper Azure hybrid integration. If you are planning new server deployments or migrations from Server 2016 (extended support ends January 2027), Server 2025 is the recommended target.

Download Windows Server 2025 Evaluation ISO

Evaluation & KMS Keys

Note: Windows Server 2025 Essentials uses a retail product key model and does not have a public GVLK for KMS activation.

Windows Server 2022 — Evaluation & KMS Keys

Windows Server 2022 introduced Secured-Core Server, TLS 1.3 by default, improved DNS-over-HTTPS, and Azure Arc integration. It remains widely deployed in production environments and is in mainstream support until October 2026.

Download Windows Server 2022 Evaluation ISO

Evaluation & KMS Keys

Applying the key via DISM (if slmgr fails on evaluation editions)

DISM /online /Set-Edition:ServerStandard /ProductKey:VDYBN-27WPP-V4HQT-9VMD4-VMK7H /AcceptEula

Windows Server 2019 — Evaluation & KMS Keys

Windows Server 2019 remains one of the most common server operating systems in enterprise data centres. It is in extended support until January 2029. If you are running Server 2019 in production, it continues to receive security updates for several more years.

Download Windows Server 2019 Evaluation ISO

Evaluation & KMS Keys

Command line key installation

slmgr.vbs -ipk WMDGN-G9PQG-XVVXX-R3X43-63DFG

Rearm the evaluation

slmgr.vbs -rearm

The evaluation period is 180 days and can be rearmed up to five times.

Windows Server 2016 — Evaluation & KMS Keys

Windows Server 2016 is currently in extended support, which ends on January 12, 2027. If you are still running Server 2016 in production, now is a good time to start planning your migration to Server 2025 or 2022. Extended support means security updates only — no new features or non-security bug fixes.

Download Windows Server 2016 Evaluation ISO

Evaluation Keys

The primary evaluation key for Server 2016 is:

NCPR7-K6YH2-BRXYM-QMPPQ-3PF6X

All Edition Keys

Rearm the evaluation

slmgr.vbs -rearm

The evaluation period is 180 days and can be rearmed up to five times (up to 900 days total).

Command line key installation

slmgr.vbs -ipk NCPR7-K6YH2-BRXYM-QMPPQ-3PF6X

Windows Server 2012 R2 — Evaluation & KMS Keys

Windows Server 2012 R2 reached end of extended support on October 13, 2023 and no longer receives security updates. If you are still running Server 2012 R2, migrating to a supported version should be a priority. These keys are provided for legacy lab and testing use only.

Download Windows Server 2012 R2 Evaluation ISO

Activation note

For Windows Server 2012 R2 evaluation editions, you may not need a key at all — the evaluation copy often activates automatically for 180 days. If you see an activation prompt, try running the rearm command first:

slmgr.vbs -rearm

If that does not work, apply the evaluation key below.

Evaluation Keys

Primary evaluation key:

D2N9P-3P6X9-2R39C-7RTCD-MDVJX

All Edition Keys

Command line key installation

slmgr.vbs -ipk D2N9P-3P6X9-2R39C-7RTCD-MDVJX

Windows Server 2012 — KMS Keys

Windows Server 2012 (non-R2) reached end of extended support on October 10, 2023. Legacy lab use only.

Windows Server 2008 R2 — Evaluation & KMS Keys

Windows Server 2008 R2 reached end of extended support on January 14, 2020. These keys are provided strictly for legacy lab environments. No production use is recommended.

Evaluation Keys (180-day trial, up to 5 rearms)

Windows Server 2008 Evaluation Keys

Windows Server 2008 — KMS Keys

Windows 11 & Windows 10 — KMS Keys

The following KMS client keys apply to both Windows 11 and Windows 10 editions where noted. These are GVLKs sourced from Microsoft’s official documentation.

Windows 8.1 — KMS Keys

Windows 8 — KMS & Dummy Keys

KMS Client Keys

Dummy Keys (install without activating)

Use these in MDT or SCCM task sequences where you want to progress past the product key screen without activating the installation.

Windows 7 — KMS & Dummy Keys

KMS Client Keys

Dummy Keys (install without activating)

Windows Vista — KMS & Dummy Keys

Windows Vista reached end of support on April 11, 2017. These keys are provided for legacy lab and historical testing use only.

KMS Client Keys

Dummy Keys (install without activating)

Evaluation ISO Downloads

All evaluation ISOs are available for free from Microsoft’s Evaluation Center. You will need a Microsoft account to register, but no payment is required.

Glossary

GVLK (Generic Volume License Key) Microsoft’s official term for KMS client keys. These keys are publicly documented and configure Windows to activate against a KMS host on the local network.

KMS (Key Management Services) A Microsoft activation technology for volume licensing environments. A KMS host server on the local network handles activation requests from KMS clients. Clients must contact the KMS host at least every 180 days to remain activated.

MAK (Multiple Activation Key) An alternative to KMS activation. A MAK allows a set number of activations directly against Microsoft’s servers. Used in environments where machines cannot reach a KMS host.

Evaluation Edition A time-limited version of Windows or Windows Server provided by Microsoft for testing purposes. Evaluation editions are fully functional but expire after 180 days unless rearmed.

Rearm The process of resetting an evaluation edition’s 180-day timer using the command slmgr.vbs -rearm. Can be performed up to five times on most Windows Server versions.

Dummy Key A product key that allows Windows to progress through the installation process without activating. Useful in MDT and SCCM task sequences where activation is handled separately.

DISM (Deployment Image Servicing and Management) A command-line tool built into Windows used for servicing Windows images. Used in this guide to convert evaluation editions to full licensed editions.

LTSC (Long-Term Servicing Channel) A Windows release track that receives security and quality updates for an extended period (typically 5 years mainstream + 5 years extended support) without feature updates. Windows Server uses LTSC releases.

slmgr.vbs The Windows Software Licensing Management Tool. A script used to manage Windows activation, apply product keys, check licence status, and rearm evaluation periods.

Frequently Asked Questions

Found this guide useful? Leave a comment below and let us know which keys you needed — we update this guide regularly as new Windows Server versions are released.

About The Author

Andrew Armstrong

Andrew Armstrong is a UK-based IT professional with 26+ years of hands-on experience in Windows, Windows Server, SCCM/ConfigMgr, Active Directory, PowerShell, and enterprise infrastructure. He founded TechyGeeksHome in 2010 and has published over 1,500 practical guides covering real-world IT problems and solutions. When not solving IT problems, Andrew develops free Windows utilities including Ultimate Settings Panel, which has been downloaded over 850,000 times.

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