Re-Activate Your Windows XP Manually the registry

Here are the remove this kind of registry activation step if it always ask you activate after 15 days

1. Restart computer, press 'F8', go in safe mode, and log in administrator account
2. Click on Start
3. Find and Click "Run"
4. Type: Regedit
5. Click the plus next to "HKEY_LOCAL_MACHINE"
6. Click the plus next to "SOFTWARE"
7. Click the plus next to "Microsoft"
8. Click the plus next to "Windows NT"
9. Click the plus next to "CurrentVersion"
10. Delete "WPAEvents"
11. Restart computer, and key in the correct license key and activate it through telephone or internet.
12. Hope you enjoy this.
13. Thanks. 

Click here to Activate Your Windows XP Manually From the registry