How To Make Window Genuine. Make Your Window 7 Genuine. Most of you might be aware of the fact that it is possible to use Windows 7 and Vista for 120 days without activation. This is actually possible using the slmgr -rearm command which will extend the grace period from 30 days to 120 days. However, in this post, I will show you a small trick using which it is possible to use Windows 7 without activation for approximately a year! Here is a way to do that. 1. Go to “Start Menu -> All Programs -> Accessories” . Right click on “Command Prompt” and select “Run as Administrator“. If you are not the administrator then you are prompted to enter the password, or else you can proceed to step-2. 2. Now type the following command and hit enter slmgr -rearm 3. You will be prompted to restart the computer. Once restarted the trial period will be once again reset to 30 days. You can use the above command for up to 3 times by which you can extend the trial period to 120 d