We have around 5000 members of which around 10 percent are paid premium members.
We do a yearly cleanout of people who haven't added any content
There are currently 4 admins and 4 mods although there were more originally but found the forum was being over moderated.
Our forum is predominantly hunting and firearms related with various other categories like fishing and 4x4 etc, because of this it has attracted a reasonable amount of trolls and trouble makers so we are all pretty active and very decisive on whats allowed.
i guess something your forum doesn't have to be to concerned about
Free members only have access to part of the forum, while the paid members have full access including classifieds so its a bit of a club within a club then after running costs are covered from this money the rest is given back to the premium members in prizes.