It's a gray area. Key may work, it may not. Personally I would not buy from these. I would stick to well-known retailers.
If you mean advertisement on around the website of Tom's Hardware, they don't endorse it, it's advertisement.
My friend told me that more games are compatible with windows 7 is that true
No, . Most games are now compatible with Window 8.1. Some old games may not work well. New upcoming games will definitely be compatible with WIndow 8.1
It's a gray area. Key may work, it may not. Personally I would not buy from these. I would stick to well-known retailers.
If you mean advertisement on around the website of Tom's Hardware, they don't endorse it, it's advertisement.