Different places.
Ones on my brothers pc so idk where it came from, but he has said it was a cheap key. Still activated.
My windows 10 came from scd keys. Still activated.
The office key on another relatives laptop came from some site seller on bonanza marketplace. Still activated.
I even bought a $3 windows xp key and iso from ebay a while ago since there is no way to buy a key from Microsoft for xp anymore. Havent used the key yet but the iso is legit.
Also, ebay has a 30 day guarentee on everything so that may be a safer route.