Membership Plugin- Don't Want On All Sites

Recently installed Membership. I'm getting emails from the domain admins of my sub-sites that their feeds are now protected:

First off- I don't want my subsite admins to have anything to do with Membership. They won't be creating their own shopping sites there. They are the customers!

How do I make it so that the subsites admins have no Membership capabilities?

When I installed the plugin- Network Activate was the only option.