My Win 8.1 Pro installation was activated with Microsoft Toolkit (as far as I understand it, Microsoft Toolkit emulated a KMS activation server, which devices can "ping" to be activated for upto 180 days). So how come when I upgraded to Win 10 has Microsoft now given my free lifetime activation (e.g., I can format my hard drive, reinstall Win 10 clean and it'll be activated without even needing a serial key). Was this an oversight, or did they just choose to turn a blind eye to it? Surely businesses who have their machines activated via KMS could exploit this? Or am I missing something? TLDR - how come if you are KMS activated, they still let you upgrade to Win 10 and have free lifetime license?