1)First make sure that you are in the Administrative Mode. Then click on the Start & access Command Promt by typing cmd in the Search Bar.

2)Then type slmgr -rearm in the Command Prompt window & press Enter. After 45 seconds, a prompt will be displayed to Restart your computer. Just Restart, after that you will see that you have successfully extended your activation period to 30 days. This will work only 3 times, so you will get 120 days of Windows Vista without Activation...But we are going to change it.

3)Open Registry Editor by typing regedit in the Search Bar.

4)Navigate to HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows NT \ Currentversion \ SL.

5)On the right side search for a key called SkipRearm & modify its value to 1.

6)Just close the Registry Editor.

Now the default limit of 3 will be changed to 8 which means that you can use Winodws Vista for 360 Days without Activation.