for keeps adv. phr. 1. For the winner to keep.
They played marbles for keeps. 2. informal For always; forever,
He left town for keeps. Synonym: FOR GOOD.
3. Seriously, not just for fun.
This is not a joke, it's for keeps. ■ Often used in the phrase "play for keeps".
The policeman knew that the robber was trying to shoot him. He was playing for keeps. [TahlilGaran] English Idioms Dictionary ▲