The California DMV and Southern California Auto Club (AAA) both will accept the smog check certificate which will be issued by the analyser at the conclusion of the successful smog check inspection. The certificate will be valid for 60 days on a change of ownership and 90 days for a renewal of the registration. It is possible to be required to get another certificate within a short time of doing a change of ownership inspection as each vehicle registered in California is on a regular schedule of renewal which was established when the vehicle was first registered with the State and the schedule was only iterrupted when the vehicle changed owners. If  you intend to sell the vehicle soon after renewing the registration, you may find these time lines to be an important consideration in the transaction. Consult the DMV or AAA for further details.