This has been a long time coming but we have a LOT of new things implemented with this plugin.
The first one is the name. We’ve moved it from Discourse League to ProCourse Memberships to align with the rest of our plugins. (cc: @meglio) But that also means that the location of the plugin has moved underneath the ProCourse organization:
https://github.com/procourse/procourse-memberships
The next change involves payment gateways. We’ve implemented two new ones: PayPal and Stripe.
That means you now use Braintree, PayPal, or Stripe with this plugin. You can see the how-to documentation for all gateways here.
A big thanks to @outofthebox for sponsoring the work for the PayPal gateway. 
And in the scheme of things, it only made sense that we set up a demo site for this under the ProCourse name. So we created demo.procourse.co to allow us to do just that. Right now it only has this memberships plugin installed, but over time we’ll build out demos for all of our plugins on that site. (cc: @bartv)
Finally, (and since I’ve received this question a lot lately) there is NO license key restriction on this plugin. It is 100% open with no limitations. Enjoy! 
Short answer: yes
Think of it this way, a membership level is tied to a user group. That means that if you wanted to set up 25 levels that all grant access to 25 different groups that are then tied to 25 different categories, you could do that. It all depends on how you handle the security settings of the categories and the groups you add to those security settings. This plugin simply grants access to the group via payment.