Plugins can return a "restrict" array from their init function containing a list of courses on which they should display.  This is only run when the app launches.  If a user is enrolled on a new course after the app has loaded, they can pull to refresh on the dashboard page to see and access the new course. However, the plugin init functions are not re-run, so even if a restricted plugin should show on this new course, it won't.  The only way to enable it is to restart the app, but there is nothing to tell the user to do this, so they will be missing content without knowing.