I usually just went into a lab at a school/college and took the key off the side of one of their desktops. Most schools would buy the machines and they would ship with windows licenses, then they would install their own Enterprise images with a sepetate license key. So if your license key wore off the bottom of a laptop, I’d steal one from there. If it was a Pro license, they worked to install up to Wim 10. I moved to Linux for most everything, but it’s always nice to keep a key laying around in case I ever need it