"Pay later" is a payment method that increases your spending flexibility. You make a purchase and get 30 days to pay for it. "Pay later" is only available when the TWINT user meets all the eligibility criteria (age, domicile, etc.) to use it as a payment method.
"Pay later" is a service offered by Swissbilling SA (Terms of use), an official partner of TWINT. UBS, as the issuer of your TWINT App, is not involved in and assumes no liability for "Pay later".