Just like Windows Vista, Windows 7 can be used legally for up to 120 days without activating with a valid 25-character alphanumeric product key. Windows typically comes with a 30-day time limit for users to activate their copy of the operating system, but there's a command that is often used by corporate administrators to reset the 30-day countdown. The rearm command can be used up to three times without violating the Windows 7 EULA. Thus, if the user resets the countdown on the last day each time, he or she can gain up to 90 extra days to use Windows 7 legally and for free. The Windows Secrets newsletter outlined the step-by-step instructions for extending the grace period:
•Step 1: Click Start, All Programs, Accessories. Right-click Command Prompt and choose Run As Administrator. Enter your administrator password.
•Step 2: Type the following command and press Enter: slmgr -rearm (note the space after slmgr and the hyphen in front of rearm.)
•Step 3: Restart Windows 7.