Hey @zunidog - If you go to the Calendar section of your Appointments Dashboard, you can create an appointment for a date and time that has passed. While you're creating the appointment, it will ask you to add a name. If you've already created a customer profile for them, their name should pop up. After hitting Save, the Appointment will be tied to their customer profile and show up in their history.

If you're concerned about being able to send them Marketing campaigns, you can also just add them to your Appointments customer group. To do this, just select their customer profile within your Customer Directory > click Edit Personal Information > type in Appointments (or whatever you have named that group) to the Group text box.

Hope that helps!