Wordpres forum theme or plugin

Hi,

I am looking for a WordPress theme or plugin free or paid in which I can charge users for asking questions in specific groups. Other than this feature, Users can also ask questions for free of cost in specific groups. These are the core features which I am looking for.

If anyone knows about such themes or plugins, then please tell us. I have tried looking for it myself but couldn’t find out, so does anyone know about it