What does HackerNews think of vlmcsd?
KMS Emulator in C (currently runs on Linux including Android, FreeBSD, Solaris, Minix, Mac OS, iOS, Windows with or without Cygwin)
Works well without activation, if you don't mind the overlay. But what I did is that I pointed it at a KMS emulator, which is a piece of software that responds to every activation request as a positive. The internet is full of lists of servers like these, but I host it myself - basically just built and compiled this one: https://github.com/Wind4/vlmcsd
Also, my country's second hand electronics market has LTSC keys for sale for like $25. That might be worth looking into.
If you want to skip straight to the piracy, here's an open source package for you, complete with keys, hosted ironically on Microsoft servers, that uses vlmcsd: https://github.com/ekistece/vlmcsd-autokms
It's a pretty clever hack. It runs the KMS emulator locally and fakes the network connection with a TAP device from OpenVPN. Works perfectly.