Hi Pablo,
Thanks for reaching out! The simplest way to achieve this would be to limit your ticket purchases to registered users only, as mentioned here in our overview of Event Tickets Plus settings:
https://theeventscalendar.com/knowledgebase/configuring-event-tickets/#login
Setting this requirement and requiring users to register before purchasing tickets will allow them to log in prior to purchasing and specify their own billing details. This setting can usually be found at the following location after logging in:
[yoursiteURL.com]/my-account/edit-address/
Once a billing address has been added to the user’s account, these details will be automatically filled in for all future ticket purchases. 🙂
I hope that helps to get you started here! Thanks again, and let us know if you should have any other questions!