How to reset Microsoft Office 2007 product license key without reinstalling?

I recently installed Microsoft Visio 2007 but entered a wrong set of product key. Several attempts were made to find ways to enter my correct set of product key without having to reinstall the whole thing. The solution is to tweak the registry.

From the registry editor, do the following:

1. Locate and then click the following subkey: HKEY_LOCAL_MACHINE \Software\Microsoft\Office\12.0\Registration. For user with 64-bit (x64) Windows, go to HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\12.0 instead
2. From there, you should see one or more sub keys with this pattern {90120000-0014-0000-0000-0000000FF1CE}. Look through all the sub keys and find the one with string value "ProductName=Microsoft Office Professional Plus 2007" (assuming you are trying to fix Microsoft Office Professional Plus 2007.
3. After you have located the right sub key, delete registry entries DigitalProductID and ProductID.
4. Exit registry editor.

DONE! You should now be prompted to input Product Key the next time you launch Office.