drtweak :
My bad. I typed in kingquin not kinguin. Two totally different sites.
If its so big though then why does it have so many issues?
Kinguin and G2A and other site have plenty of legit game codes. People get them in contests, they are included with GPUs, giveaways, bundles, etc, theres like hundreds of ways that legit game codes end up out in the wild.
Windows (and all MS products for that matter) on the other hand is very tightly controlled in how you can buy it or get it. Aside from clear retail copies the only way you can get it is included with a PC or OEM copies. Codes that are sold by code sites are generally from bundles that are not for public use, such as educational codes, or licenses for businesses. For these to be out in the wild they are many times effectively stolen (example you have 5 extra codes from work that are not needed, you take them home and give them to friends, they stolen). However Microsoft has the ability to deactivate licenses remotely so in my aforementioned example now your boss realizes you took them he can contact Microsoft, report 5 stolen licenses, and they can disable them. Even if they are not stolen, if they are being sold cheap against the terms that they were obtained, Microsoft can deactivate them for that too. Its in the license and purchase agreements.
We have also seen the case where two different people were sold the same license code. Every couple of days the person's PC would deactivate, so they would just re-enter the code and it would activate again. After some digging we figured out that was the issue.
The big sites just sell more of them, however the little sites like you posted have the same problem.