In order for Microsoft to verify legitimate versions of Windows 7, users must activate their copies of the operating system within a finite time limit. On first inspection, that time limit appears to be 30 days, but as was the case with Windows Vista, there is a way to stretch that limit to nearly four months.
Like Windows Vista, the upcoming Windows 7 comes with a command line utility called the Software License Manager (slmgr.exe) that allows the user to issue "-rearm" switch that will reset the countdown timer back to 30 days. This command may be issued a maximum of three times. If a user issues this command at the end of each 30-day period for three times, he or she would be able to use Windows 7 unrestricted for up to 120 days.
The procedure to reset the countdown is identical to the process used for Windows Vista:
- Start the command line by clicking Start > All Programs > Accessories > Command Prompt (Run As Administrator) – or for a shortcut, hit the Windows Key + R and type "cmd".
- At the command line, enter in "slmgr –rearm" without the quotations.
- Restart Windows 7.
After the reboot, your counter will have reset back the 30 days.
Microsoft confirmed to Computerworld that this trick does indeed work. "This means [that] a total of 120 days total time is available as a grace period to customers that take advantage of -rearm," said a company spokeswoman.
Interestingly enough, the Microsoft representative said that extending the activation grace period using the slmgr is not a violation of the EULA.
This could be the perfect way to install and run your RTM disc of Windows 7 right now and stave off activation until you receive your licensed product key on October 22. Be careful to only install the edition that you intend to purchase, which could involve modifying the disc image. (Read more about this procedure at Windows Secrets.)
Of course, if you run this rearm process before your 30 days are up, you'll get fewer than your 120 days maximum. It'll be best to mark it on your calendar and set a reminder.