Hi,
I’d to create a premium section on a discourse forum for members who pay a monthly subscription. What is the best plugin to to that?
Here are the features I need:
I found these:
https://meta.discourse.org/t/discourse-premium-bt/38139
https://github.com/xfalcox/discourse-patreon
As the author, I can tell you that the Premium BT plugin is not the answer. It’s very outdated and most likely nonfunctional at this point.
I’m not familiar with the Patreon plugin but my limited knowledge of it tells me that it would work to create different payment levels that grant access to different groups. I don’t know what fees Patreon collects but I would imagine them to be fairly high.
All of that said, I’m currently in the middle of building a plugin (working title is Discourse League) that handles paid access to groups through either a subscription or initial payment or both. There are a lot of other details I want to implement but that’s the base idea that I’m working towards.
The obvious difficulty with this is payment gateways and currencies to support. My plan is to use Active Merchant for the backend. I’ll have to build in limited support on my end to make each gateway work but the long-term goal is to support every gateway in AM. That should hopefully help with the currency support.
I’m looking at early February for a limited launch for this. 
Have you checked out Paid Membership? You could only allow certain paid groups to see/post in specific categories.
I’ve done this using Stripe and Chargebee to handle the subscriptions. When someone pays I manually add them to a group that has access to a subcategory on my site. It works well 
In time I’d like to automate everything so I don’t have to do things manually.
I’m also looking down the line to possibly adding a paid/premium section to my Discourse forum.
A possible solution I’m looking into is using Memberful which isn’t a plugin but a SaaS which integrates their services with Discourse. They have a pretty detailed page on how to integrate the two. You can use Stripe with Memberful as your payment processor which is available in French.
Another way around would be to use a Wordpress plugin such as Paid Memberships Pro which would handle premium member registration (you would need a Wordpress section/landing page on your website), and a bridge/plugin to connect Wordpress and your Discourse forum.
Since your mentioned:
I’m guessing the solution/plugin would also need to include VAT %.
Based on my own experience selling online in Europe, you are going to be leaving some money on the table by not accepting bank transfer payments (some people just don’t have a credit card or prepaid credit card, or know what the heck Paypal is, or are simply uncomfortable paying for anything online unless you are a big brand like Amazon).
This already exists. It was created and supported here by @simon. It works well with Paid Memberships Pro.
Patreon Plugin may also be used with a bit of changes in Your community.