Where does "for good" come from?

Question

As a foreign English speaker, I always wondered if "for good" is an old style English phrase, or it is relatively new. For me, it seems like an old style phrase, but I don't know anything about etymology.

Can you shed some light on it?

Answer 1

In the sense as a valid conclusion; hence, as a final act, finally it is first recorded in the early sixteenth century. It remains in current use.