cmd as admin
slmgr -rearm
What you have to realize is that if you apply this fix while you can still see your desktop background, it will rearm the system for another 30 days, up to a maximum of 3 times.
If you apply the fix after you lose your background (ie your desktop wallpaper background goes black, and you get the notification at the bottom right of the screen), you need to first uninstall the kb971033 update, then apply the fix. It will then be a PERMANENT fix. If you're running a Remove WAT program, WAT needs to be restored first. Never mind WAT, if you have no idea about that.
If you have exceeded the maximum allowed rearm, you will get an error message just like this,
" Error: 0xC004D307 The maximum allowed number of re-arms has been exceeded. You must re-install the OS before trying to re-arm again "
Well, here is a fix for that, Just do:
Locate the following in your Windows Registry,
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SoftwareProtectionPlatform]
"SkipRearm"=dword:00000000
After your 3rd reset this key will be 00000000 - simply change it to 00000001
Read more: http://www.bench3.com/2010/03/remove-windows-not-genuine-watermark.html#ixzz3StSgeaBY
