What's the difference between customers and memberships?

Restrict Content Pro version 3.0 added separate pages for "Customers" and "Memberships". If you've just upgraded from version 2.x you might be wondering what the difference is between these two. 

Customers

Customer records are like user profiles. They contain information such as the member's name, original join date, email verification status, and last login date.

Memberships

Memberships contain information about the membership itself, such as the status, expiration date, payment gateway that was used, etc.

Separating out customers and memberships was done in preparation for supporting multiple memberships per customer in the future. The logic is similar to an e-commerce site that sells products, where you may have "customers" and "orders". Each user will only have one customer record, but each customer may have multiple orders. In the future of Restrict Content Pro, each user will have one customer record, but it will be possible for each customer to have multiple memberships.