BuddyPress makes it easy to start your own community. If you are planning to restrict access to premium features, you may want to give plugins such as Paid Memberships Pro community a look. It is a handy plugin that restricts access to profile pages and members directly. You can also restrict access to your forums, media, and other parts of your website. Admins can redirect users to sign up or membership level page.
This plugin lets you set a default membership level upon registration. It can be set up to automatically invite or assign members to specific groups. This plugin can prevent members from sending public and private messages. It supports different fields for different membership levels. This could come handy for online courses, dating sites and other private communities.