Before and after the official release of Windows 8 there were a lot of people looking for methods to activate their copy of Windows 8 without paying for it. Illegal Key Management Servers (KMS) were setup that could be used to activate Windows 8 for at least a while. There was also a method found that converted a pirate copy into a full legal copy by using an illegal KMS together with a Windows Media Center (WMC) key. Microsoft provides these WMC keys until January 31st 2013, so early buyers of Windows 8 are able to get WMC for free.
Once the KMS + WMC key method got onto tech sites, many users benefited from it. But those who have activated Windows 8 this way are now complaining on forums that the operating system is no longer activated. An unactivated/deactivated Windows 8 installation can be easily recognized by watermarks on the desktop that tell you you’re using an inactivated copy. Many users who installed updates for Windows 8 found their computer to show these watermarks again.
Once the updates KB2792009, KB2790920, KB2788350 and KB2785094 are installed the fun is over. According to the Microsoft website these updates fixes an issue with streaming video from WMC to the Xbox, improve Bluetooth audio playback quality and resolve an issue with the Windows Store when an app is installed to multiple accounts on the same computer. The website does not state anything about deactivating illegitimate activated installations of the operating system.