You can sell group memberships with multiple members using the Group Accounts add-on with Restrict Content Pro.
A member may form a group account that has a certain number of “sub accounts.” After registering, the group owner may add or import accounts to provide group members with membership access.
For instance, a teacher at a school might create a group account for a class and then add each student as a member of the group, giving them all access to the website’s members-only resources and content.
Group members never have to enter any payment information or be concerned about their account status because billing and account control (cancellations, upgrades, etc.) are only available to group owners. This makes it simple for businesses and other large groups to control who has access to what information without requiring that each member have their own account.