Extending the Evaluation Licenses
The lab runs on time-limited evaluations: 180 days for Windows Server 2025 and 90 days for Windows 11 Enterprise. Windows includes a built-in tool, slmgr.vbs, to check the timer and reset (rearm) it. Each VM has its own timer, so rearming DC01 does nothing for the clients.
All commands below run in a Command Prompt opened as administrator, on the VM you are checking.
Check Activation and Time Remaining
Section titled “Check Activation and Time Remaining”slmgr.vbs /xprShows the expiration date. Run this occasionally on each VM, and set a reminder a few days before any of them expire.
The Server evaluation must activate online within 10 days of install or it starts shutting itself down hourly. This normally happens automatically. If /xpr says the machine is not activated, confirm it has internet access and run:
slmgr.vbs /atoRearm When the Evaluation Is Almost Up
Section titled “Rearm When the Evaluation Is Almost Up”A rearm restarts the evaluation period from the day you run it, and you only get a limited number of them, so wait until the clock is nearly out. To see how many rearms a VM has left:
slmgr.vbs /dlvLook for the remaining rearm count in the dialog. Rearm counts vary by build, so this number is the authority, not anything you read online.
If at least one rearm remains:
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On DC01, shut down the client VMs first so they are not using domain services mid-reboot. On a client, keep DC01 running.
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Run:
slmgr.vbs /rearm -
Restart the VM.
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Verify:
slmgr.vbs /ato, thenslmgr.vbs /xpr. The expiration date should have moved forward.
If the date did not change or /rearm is rejected, do not keep repeating the command. Check that you ran it as administrator and restarted afterward. If the rearm count is zero, that installation cannot be extended: rebuild the VM from fresh evaluation media (or use a licensed edition). For DC01, rebuilding means rebuilding the domain, so plan before its final period runs out.
What Not to Do
Section titled “What Not to Do”Skip the workarounds you may find online: rolling back the clock, registry hacks, activation tools, or restoring old snapshots to reset the timer. They are unreliable and can break the lab. Rearming and rebuilding are the supported paths.
Microsoft documents the evaluations at the Windows Server 2025 and Windows 11 Enterprise Evaluation Center pages, and the tool itself in the slmgr.vbs reference.