PAAR stands for Placement, Alumni, Affiliates and Returners. The job of the PAAR rep is to make sure these groups are properly represented and included in hall activities.
When you leave DC, you can still come back and get involved even if you move to town. But make sure you pay your £10 affiliate fee to cover any events you come back and join in with. The fee also means you can participate in DC IMS events even though you no longer live in DC.