That's a great question, hamids54. I think it will come down to how committed your members are to the topic and community, and what the benefits of the premium membership would be.

Possible benefits:
- Member badge/recognition as a supporter
- Relaxed posting rules in private area
- Reduced noise level in private area, more serious discussion
- What else can you come up with?

I don't know if your community will find those or other benefits attractive. A few cautions:

- The more content you have behind a pay wall, the less search traffic you will get. In most of the forums I know, the main source of new members is organic search traffic.
- Generally, only a small portion of active members will pay to play. If you could get 10% of your active people that would probably be good, but that's a guess.
- If your best members start talking in the private area, the quality of discussion in the rest of the community may go down. Probably not a big risk, but watch out for that.

Good luck, let us know if you try it!

Thanks rogerd for your advices.

I am evaluating all aspects of this action what I can do for
Premium Membership service that attracts users to pay and not hurting progressing of my traffic.I must think very much.

my users would like just to read articles and news and they don`t interest to open new topic or take part a topic . they are using my forum as a big service blog I am not happy for this situation but happy for my traffic is growing 60% per year any way.

my users find anything they want in more than 500 forums...
may be creating a private clinic that some users don`t want
to be public doesn`t hurts my traffic... just thinking.

Since it's a medical site I'd allow paying members to post pictures in the paid member only section for diagnosis/discussion. Not everyone wants to post a picture in a public area, just an idea. This is where being somewhat anonymous online is a benefit, who wants to post a picture of a bump on your foot in your facebook or google pages where everyone you know will get grossed out? :)

I don;t know if this would apply to your forum but the issue with paid membership on my forum is many long term members who contribute a lot that aren't going to be too happy that someone else is getting better access because they paid for it.

I have not let my users to use signature position and even avators as yet from 8 years ago. then the two items will be some new offers for the ones pay for Premium Memberships.

I am thinking about what offers will be as a health forum for Premium Memberships.maybe one thing is introducing medical staff by advertising topics .

I don`t think medical online consult will be possible with the money users pay bc even one time consulting is expensive and is not possible to get unlimited consulting with one time monthly paying.