If that's the case the easier solution would be to have a welcome page of some type that holds the payment processor API.
An owner could set up a feature/ payment table that visitors could decide to just read and post or create new content for a one time fee ($.99)
All the owner would need to do is create an additional field collecting user names on the payment application and add that to members.txt under "threads".
A couple sticky points would be:
- if a site has a bunch of sub-forums and needing to copy that members.txt to all those folders.
- manually managing paid members because the welcome page described above is just an intro page to the forum pages and not tied to the NNF software at all.
This intro page to the forum could also have various data pulled and arranged like Latest posts, Popular topics, Featured, etc, as well as the membership table.