The CPL is the licence you will be issued with. Attached to the licence are ratings. Those will be the SEP, MEP, and MEIR. The licenceis renewed by paying a fee to the CAA every 5 years. To renew the ratings however you will need to meet certain criteria. I suggest you check Lasors where you will find all the necessary info. The one that you really need to keep current is the MEIR. The SEP and the MEP are not required for a Type Rating, but the MEIR is. It would be a better idea howver to try and keep all ratings current, keep flying, and keep yourself as employable as possible.