turn·key 
(tûrnkē′)
(tûrnkē′)n. pl. turn·keys
The keeper of the keys in a prison; a jailer.
adj.
1. Supplied, installed, or purchased in a condition ready for immediate use, occupation, or operation: a turnkey computer system; a turnkey housing project.
2. Of or relating to something supplied, installed, or purchased in this manner: a turnkey agreement.