CERN operates and maintains several large cryogenic systems including those serving the LHC complex and its associated detectors, together with cryogenic Test Facilities and distribution services. Outsourcing of Operation and Maintenance to an industrial partner was implemented in 2016. It allows the cryogenics group to activate different level of services starting from basic technical support up to full delegation with result oriented obligations for availability and helium inventory management by means of dedicated contractual key performance indicators. After almost three years from the implementation of this complex service contract in a context of intensive Operation & Maintenance campaigns of CERN accelerators, detectors and test facilities, this paper will report on the obtained results, emphasizing on technical, organizational and economic performance. Additionally the paper intents to share lessons learned from the implementation and follow-up of such major outsourcing. Finally the paper will describe the expected evolution of specific needs with respect to the provided services during the Long Shut Down 2 (2019-2020) of the CERN accelerators, detectors and test facilities, including the phase of resuming operation of the cryogenic plants and ancillary infrastructure.