Seems like quite a lot of people are misremembering how Activation and similar technologies worked. Retail versions of Windows XP required Activation by intern

Seems like quite a lot of people are misremembering how Activation and similar technologies worked. Retail versions of Windows XP required Activation by internet or phone. Volume Licensing customers could bypass Activation with a Volume Licensing key - like the infamous key mentioned by others here that began "FCKGW-". This was a valid key prior to Service Pack 1 (SP1). SP1 blocked it and several other "widely known" keys. Windows Vista and later made Activation mandatory for Volume Licences to stop this sort of key abuse. Someone has mentioned Windows Updates imposing the Activation requirement - they are probably thinking of Windows Genuine Advantage (WGA) - https://en.wikipedia.org/wiki/Windows_Genuine_Advantage https://en.wikipedia.org/wiki/Windows_Genuine_Advantage. WGA was a separate technology to Activation. It added further checks to detect various types of pirated copies. One thing that's often overlooked about Activation is that it was only intended to deal with "casual piracy" - where people buy or obtain a genuine copy of Windows, but then try and use it on more PCs than the licence permits.