It is possible to use Windows 7 and Vista for 120 days without activation. 

With this trick you can use Windows 7 without activation for approximately120 days or more.

Follow the instructions-

1. Goto “Start Menu -> All Programs -> Accessories” . Right click on “Command Prompt” and select “Run as Administrator“. 

If you are not the administrator then you will have to enter the password, or else you can proceed to next step.

  

2. Now type the following command and hit enter 

               slmgr -rearm

3. You will be asked to restart the computer. Restart the computer.Once restarted the trial period will be once again reset to 30 days.

Follow the above steps three times for 120 days usage. This is the max.

 4. Open Registry Editor (type regedit in “Run” and hit Enter) and navigate to the following location-

5. In right-side pane, change value of SkipRearm to 1. 

6. Now you will be able to use the slmgr -rearm command for another 8 times so that you can skip activation process for another 240 days. So you will get 120 + 240 = 360 days of free Windows 7 usage.

120 days using “slmgr -rearm” command before registry edit

+                                                                                                                                                                  

240 days using “slmgr -rearm” command after registry edit

 =      360 Days