Hey Francesca,

Thank you for purchasing Amelia, and for reaching out to us.

Currently, the Membership feature doesn't exist in Amelia but it is on our "to-do list" and it will be added sometimes in the future. It is planned to be added for Pro and Developer licenses. 

As for the approach regarding logged-in members. You could install a membership plugin, which will block access to certain pages. So, you can create a page that non-logged-in members can access, but it will not be seen by logged-in members. 

On that page, you can create a service that will be free. Once you enable "Automatically create Amelia Customer user", when the non-logged-in users book an appointment, they will be subscribed as members and registered as customers in Amelia, so they will no longer be able to access the page where the free service is.

Then, on another page, for logged-in members, you can add a paid service, and that page would not be visible to non-logged-in users.