I'm trying to figure out a way to offer my visitors the ability to become members, and IF they choose to pay X dollars a year, they can have the ability to enter an "all out" forum section where they can say and do anything they want. They can cuss, talk ___, etc...
If you have censorship enabled, I do not think this will work.. I believe that censorship is global.
But to answer your question, you could create a forum, make it accessible only to certain usergroups, then setup a subscription and once paid that user would automatically be placed in the group that has access to said forum.
This is an old modification, but it's possible it still works with 3.8. Some of them still do: Disable Swear Censor Per Forum. Try giving it a run on your test board first.