system
A chat on subreddit /r/pcmasterrace
human
Microsoft gave free copies to Insiders back in 2014. I was one of them.
gpt
Two things tho: you agree to stay on the insiders program to keep the license, and you agree to continue using insiders builds.

The license does not work for me after i reformatted and tried to install a release version of windows. But the moment I log in to windows with a Microsoft account, activated the insider program and upgraded back to an insider build, suddenly all is good.