Hi oxwaller,
here is one of the best Membership Plugin in the Store regular updates, support from Artmedia perfect.
Paypal is already integrated in the plugin so you don't need the PayPal plugin. (Perfect)
despite the price you can only recommend it.!!
Thanks Artmedia for the great plugin
PS: if the "Add coupon code for discounts e.g. -25% ect. for the membership form" is integrated, it will again be one of the best plugins in the store. :-)
so far there are only - "you can add vouchers" for free membership :-(