Hello M. A. Allawi,
I'm John an Independent Advisor and a Microsoft user like you. I'll be happy to assist you today.
Currently the price for Windows 10 Home - $139 and Windows 10 Pro - $199 from the official Microsoft Store. Those activation keys were way more cheaper and too good to be true. If you will purchase it directly from Microsoft, you will be getting a valid and genuine license. There's no guarantee that those activation keys that can be bought on a cheaper price from a local market were genuine. Probably the keys will work for a while but It might be blocked from use later by Microsoft when the key is reported stolen. It could be a pirated copy which will later have issues with activation.
Tips for safer shopping – in person or online
https://www.microsoft.com/en-us/howtotell/shop....
I hope this helps! Please let me know if you have any further concerns.
Sincerely
John DeV
Independent Advisor