To extend your activation grace period on Windows Server 2008 and 2008 R2 check the steps below:
Click Start, and then click Command Prompt.
Type slmgr.vbs /rearm, and press ENTER.
Restart the computer.
The activation period of your Windows has now been extended for 60 days. You can re-arm up to 3 times giving you a total activation period of 180 days.
You can find out how much time is remaining in the activation period by running the same command with a different switch:
Type slmgr.vbs /dli, and the current status of your activation period is displayed.
