„Turnkey“

A term for a method of construction whereby the contractor assumes total responsibility from design through completion of the product and release to the client in a stage so complete that the buyer need only to turn the key to open the door and walk into a facility that is ready to operate.

Source:

Kerzner, Harold. (2009). Project Management: A Systems Approach to Planning, Scheduling, and Controlling. John Wiley & Sons. pp. 503-504.