Here’s a November 2022 article concerning how to get a Windows 10 product key for cheap:
By the time these keys all stop working is about a day before there will be Windows 12.
It may be interesting to some that I wrote some software for an HP mainframe back in the 70’s. Even though HP upgraded operating systems and completely changed to RISC architecture and completly chnaged hardware, etc, my software still ran after Y2k and if there are still those mainframs with current software, my programs will STILL run! It is called Backwards Compatability and Microsoft does not care at all about that. The debacles of 32 bit vrs 64 bit and so on are obvious. In fact, I can run that mainframe operating system AND my software under VM on my Win7 box. There is software made by Microsoft for windows 7 that doesn’t run under Windows 7. If there was a case, I would rest it now. Maybe just a mike drop?
I have taken the route of buying a cheap Windows 10 Pro key from a third-party seller. The first key the seller gave me didn’t work, so I contacted the seller, and they gave me a new key which worked without any problems after sending a screenshot of the problem. 
It is important to see the terms and conditions of the sale to make sure you’re protected if problems arise. 