Extend Windows Server Trial: slmgr /rearm and /dlv
The Evaluation edition of Windows Server runs for 180 days. You can extend the evaluation period with slmgr /rearm — it resets the counter, and Microsoft itself permits this for testing. To see how many days and how many resets are left, use slmgr /dlv. Here is the process step by step.
Important: this is for evaluation, not production
The rearm mechanism was built by the vendor specifically for evaluating and testing the OS. Production use requires buying and activating a full licence. What follows is the legitimate way to extend the trial (evaluation) period while you evaluate the system.
Step 1. Check the current licence status
Open Command Prompt or PowerShell as Administrator and look at the detailed information:
slmgr /dlv
In the window that opens, pay attention to two fields:
- Time remaining — how many minutes/days are left in the period;
- Remaining Windows rearm count — how many resets you still have.
For a short view of the remaining term:
slmgr /xpr
Step 2. Reset the counter (rearm)
When the trial period is close to running out, run:
slmgr /rearm
The command reports success and suggests restarting the server.
Step 3. Restart the server
The change only takes effect after a reboot:
Restart-Computer -Force
After the restart run slmgr /dlv again — the timer will be reset to a new period.
How many times you can extend
| Metric | Value |
|---|---|
| Length of one period | 180 days |
| Rearms available | usually up to 5–6 |
| Total evaluation time | roughly 3 years |
| Command to check what is left | slmgr /dlv |
Remaining Windows rearm count drops by one with every slmgr /rearm. Once it reaches zero the trial period can no longer be extended and a licence is required.
What to do when the rearms run out
When the attempts are exhausted you have two legitimate paths:
- Buy a key for the edition you need and activate the system with
slmgr /ipkandslmgr /ato. - Convert Evaluation to the full edition if you hold a licence — through
DISM /online /Set-Edition.
Frequently asked questions
Is using slmgr /rearm legal?
Yes, the rearm mechanism is officially provided by Microsoft for evaluation editions and for extending the evaluation period. What is not legal is running a trial as a permanent production solution without a licence.
Why does slmgr /rearm return an error?
Usually the attempt limit is exhausted (Remaining Windows rearm count = 0) or the command was run without administrator rights. Check the counter with slmgr /dlv and start the console as Administrator.
Is any data lost during a rearm?
No. The reset touches only the activation counter. Installed programs, files and settings stay in place; all that is needed is a reboot.
How do I see how many days are left in the trial?
Run slmgr /dlv and look at the Time remaining field, or use the short version slmgr /xpr, which shows the expiry date.
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