product key unacceptable

MERGED QUESTION
Question from justjk : "product key after resert"



Being "online" does not mean it is activated.
Win 8 will give you a 30 day grace period. And then increasing level of nag.

Currently, you have no idea where the OS on it came from.

And for any used system, your very first move should be a full wipe and reinstall. You have no idea what the previous owner(s) had in there.