Add a service count indicator on the appointment details that shows how many times the customer has done that service in the past. For example, if the customer has already completed 4 60min massage appointments, the schedule would have an indicator (when you click to see details) that shows they've completed 4 previously so we know it is their 5th.

This would help provide better conversations with clients, and better staff awareness when a client is completing series of scheduled/prescribed treatments.