Well, it is dated, but sometimes I need to know how to do so.
If that machine is already activated, we need to reset it first. [if not, you can skip this part] >> Registry Editor | HKEY_LOCAL_MACHINE\\Software\\Microsoft\\WindowsNT\\Current Version\\WPAEvents >> modify OOBETimer, by typing any number, then OK That's it.
Changing product key >> Start | run "%systemroot%\system32\oobe\msoobe.exe /a" >> select Yes, I want to telephone a customer service representative to activate Windows >> click at Change Product Key at the bottom | then put new one in & click *update* at this point, you can go back and activate by the internet or whatever you want.