CRM
A CRM (customer relationship management system) is a database of the people who have interacted with a business, holding what each one did and what should happen next.
The "next" half is what separates a CRM from a contact list. A spreadsheet of email addresses records who exists; a CRM records where each person is in a process and what is owed to them, which is what makes it possible to notice that someone has been waiting eleven days.
The usual failure is not choosing the wrong CRM but keeping the wrong one populated. A CRM is only as useful as it is current, and one fed by hand stops being current the first busy week.
That is why where the records come from matters more than the feature list: if the forms, the booking calendar and the checkout write to it directly, being current is the default rather than a discipline.