Disable automatic activation in Windows Vista

If you install Microsoft Windows Vista without activating any license key during the setup, you have a 30 day trial version of Windows Vista installed. After the 3rd day of your trial, Windows Vista start to automatically activate your license key over the internet. You can disable this automatic activation by making a change in the registry as shown below :

Note : You must have administrator credentials to make these changes.

1. Open the run dialog by pressing the key combination Windows Key + R. In the run dialog type regedit and press Enter. This would open the Registry Editor
2. In the Registry Editor, navigate to the following key:
   HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SL\Activation
3. In the right pane, double click on the value named Manual and change the value to 1
   
4. Restart the computer for the changes to take effect.