It is against the rules of Tom`s hardware, to ask for a windows licence key to activate it.
If you do not have the original licence key that came with the Os. Then buy another version from Microsoft.
We will not provide you with a key, as it is classed as theft of software.
And piracy!
If you have no COA sticker as said, that is your only option.
Buying a new version of the windows OS.