"Cut your losses, put that 'purchase' into the column labeled "Never do this again", and buy a valid OS from an authorized retailer. Amazon, Newegg, Microcenter, etc...
(and no, ebay or G2A are not an authorized retailers)" YEA.... he's right.
Read this, regarding that from reddit
www.tomshardware.com/answers/id-2736528/windows-key-blocked-copy-recognized-genuine-ssd-fix-problem.html
Paypal provides seller protection for 6 months so if you do buy a bad key you can easily get your money back. The price difference being around $100, it is well worth the small risk of buying from a bad seller. In addition, you can report a bad seller to the mods and they will add them to the banned list.