earn (one's) keep

To perform sufficient work or help in exchange for money or housing. If you're going to live here rent-free, then you need to earn your keep by helping out with the cooking and cleaning. That boarder earns his keep by doing maintenance in the building. I have no problem earning my keep, if need be. I'm actually a pretty good cook.

earn your keep

be worth the time, money, or effort spent on you.

ˌearn your ˈkeep

be useful, helpful, successful, etc. enough to balance any costs that you cause: Jill more than earns her keep with the help she gives me around the house. ♢ Though it’s expensive to buy and maintain, the new computer is earning its keep as we’ve been able to reduce the number of staff.