We don’t hold any card details anywhere on the Line-Up system.
All payments are handled by Stripe, who are certified to PCI Service Provider Level 1, the most stringent level of certification.
As with any e-commerce transaction, card details are encrypted and held by the payment processor (Stripe in this instance) in order to mange things like refunds, fraud prevention and for auditing purposes.
Stripe provide us with a "token" which enables us to make the card available to the returning customer when logged in so they can check-out even quicker when they next book. If a customer does not wish to have the card available in their account then they can remove it and anytime by going to any ticketing widget on the vendors website, adding a ticket to the basket and then logging in with their email and password from the previous purchase. From there they will see a link to "change payment card" and they can delete the card at that point.
More information on security at Stripe can be found here