Gah, I had written a long entry, then clicked outside the comment box by mistake and everything was gone.
OK, once again, short version this time. I'm trying to configure my Multisite network with Membership so that subscribers have access to some features provided by plugins, while non-paying users don't.
I added a plugin to the negative area of the Visitor/Stranger access level. The user still has full access, the setting did nothing. Not what I expected as Part VIII of the documentation says I can set permissions to access "features".
Then, section 8.20 says that Negative means that "users cannot install plugins when selected". Install? In Multisite, no user except the super admin can install plugins. I don't need to restrict what is not possible anyway.
Is content the only thing I'm able to control, or am I missing something?