Where do people get licensed windows stickers for sale and is it legal to buy and use them?

Question

Law in IT

At Internet auctions, there are many offers for the sale of "original", "not activated", "licensed" stickers for different editions of Windows at affordable prices. Where do they come from people - do they take them out from organizations or do they print them themselves?
Are there any pitfalls in their acquisition if you want to use licensed software?
At least from the point of view that one fine day Windows does not write that it is not valid.
I see that there are even separate sites where licensed kits (boxes, disks, stickers) are bought that people have left after activation.

Answer 1

YES, they are almost all activated, how many I bought them, it's just that in many countries the presence of a sticker on the system unit is proof of a license.