Could someone explain to me about windows product keys. I would like to know how they work.
I have got a program that shows me the product key of my operating system. Thought it would be a handy tool (if I get a used PC with the windows sticker wore off). I ran the program, it gave me a 25 digit key but it doesn't match sticker on my laptop?
My laptop then died, I had the key on the sticker plus the key that the program recovered for me and I tried to reinstall the same operating system on a desktop and it said that it wasn't a valid key.
Could someone explain keys or point me to a page

Thanks