I think that a god way of promoting this support feature (and get a ton of pages in google index) is by show the first post to everyone and the rest of the content to the people who have a client account who in my context is people in a targeted user group(s).
It will be also nice to display a promo message like "Buy a license to read the rest of this content", view the thread prefixes so the people could tell if the issue is solved, invalid, pending, etc.
I'm willing to pay for this add-on and I need to be able to tune the permissions of this system in the admin control panel. I will like to have this options in the edit forum screen, something like show only fist post and then select the user groups that can see all the posts and also define a text to indicate that you are not seeing the whole content because you need to be a client or anything that I could type on a textarea.
I hope that some coder can get into this and earn some money