Hello Rob,

Thanks for reaching out to us.

By default, each customer can access the booking form and make an appointment through the booking form, but the workaround would be to use membership plugins (like MemberPress, Ultimate Member, etc.) since this plugin allow you to create a page that is inaccessible to some (for example non-logged-in users). You can also create custom logic, so a user can access this page once a month (for example), but we're not sure about that, since we don't work with Membership plugins. 

Amelia doesn't store any credit cart information, only the appointment information like customer name, email, payment status and etc.

Regarding rental agreements, you can use custom fields to collect additional information from customers. For example, you can use this workaround for "terms and conditions" 

Add a link to Terms & Conditions, you can use "Checkbox" or "Radio" custom fields. In the custom field you need to add an anchor tag like this:

<a href="https://wpamelia.com/terms-and-conditions/" target="_blank">Terms & Conditions</a>

So this text appears as a hyperlink that opens a new tab (target="_blank") and takes the customers to your Terms & Conditions without them leaving the booking form. So the custom field on the back-end would look like this:

As you can see, we made this radio button a mandatory field, so no one can book an appointment without checking the "I agree" button.

I hope it helps.