Feels too much complicated logic. It could be sharply simplified and cleaned up.
First of all, on EnterWorld you should only have a reference of a method, example: onEnterWorld(PlayerInstance player) reference, you dont need anything more there.
Then make sure on server launch/shutdown you load/save such a map "Map<Integer, Map<Long, VipType>>" which structure will actually be explained as {playerObjId, (timeToExpireOnMillis, VipType)}.
Once you have such structure the only thing you actually have to do in onEnterWorld is to check if the player that is logging in has any Vip Type time active by comparing timeToExpireOnMillis with currentTimeOnMillis and then give him the coresponding Vip benefits.
You could also make such check on real time by scheduling a task at fixed rate.