I paid for 90 days about 6 months ago. I just went into that 90 days a little over a week ago. I have 75 or so left. My reviews and problem reports had really added up.

30 days for the first two reviews, then 15 days per review accepted, and 2 days per problem report accepted. If you are paying for VIP, then all your earned free days go into your VIP "bank." If you cancel your paid membership, or let it expire, then the banked days kick in.