While the Microsoft Windows 8 Upgrade Key is intended only for upgrades from earlier Windows versions to Windows 8, there could be valid genuine reasons when a user would like to do a clean installation of Windows 8. If a user tries to do a clean install activation using the upgrade key they are shown the error below and no activation occurs. Luckily, if a user owns valid license key for previous Windows version they can use a simple registry hack (I assume legally) which enables them to bypass this activation error message.

Invalid Product Key

"The following failure occurred while trying to use the product key:
Code:
0xC004F061

Description:
The Software Licensing Service determined that this specified product key can only be used for upgrading, not for clean installs."

Microsoft offered super cheap Windows 8 Pro upgrade keys and users have been asking whether they can perform a clean installation and activate Windows 8 using the upgrade product key, and the answer is "No" and "Yes" !!

Confused!, well Microsoft will detect whether you upgraded or clean installed and block users from activating using the upgrade product key showing the error as below. But, users can still get the product key working by doing a little registry hack which will enable them to activate - this is not fair (or legal I guess).

After installing Microsoft Windows 8, the very first thing you should be doing is to activate your copy using an genuine product key. Microsoft Windows 8 activation procedure is similar to Windows 7 and all you need to do is to supply the activation application your correct product key and have an active internet connection.

Microsoft Windows 8 will automatically prompt a user via "Action Center" notification as soon as an active internet connection is detected after installation, all a user needs to do is to follow onscreen instructions (as also shown in images below) and complete the procedure which hardly takes few minutes for online verification of your product key with Microsoft licensing servers. Without activation of Windows 8, users are restricted to use all features of the operating-system like Personalization and are nagged from time-to-time.