However, the Media Center upgrade reportedly works even on KMS-authorized installations of Windows, turning KMS-hacked PCs into permanently-authenticated copies of Windows. With KMS, you need to re-activate Windows every 180 days, making this sort of piracy rather limited in effectiveness. Normally, KMS provides a way for corporate IT people to activate copies of Windows on a local network without having to make each PC contact Microsoft directly for authentication during the install process, but it has also given rise to pirate KMS servers, which hand out activation keys over the Internet. That provides a neat workaround for pirates who exploit a weakness in Microsoft’s Key Management Service (KMS) to get temporary access to copies of Windows 8. However, applying the upgrade has an unintended side effect: It permanently activates the copy of Windows 8 that you’ve applied it to. The Media Center upgrade, which Microsoft is offering through January 31, 2013, includes Microsoft’s tools for watching and recording live TV.

Windows 8 media center keys