Keeper

noun

1. One who keeps something.

   "Finders keepers; losers weepers]."

2. A person or thing worth keeping.
3. A person charged with guarding or caring for, storing, or maintaining something; a custodian, a guard; sometimes a gamekeeper.
4. The player charged with guarding a goal or wicket. Short form of goalkeeper, wicketkeeper.
5. A part of a mechanism that catches or retains another part, for example the part of a door lock that fits in the frame and receives the bolt.