Payments
Payment tokenization
Payment tokenization is replacing card details with a reference token so a merchant can charge a stored credential repeatedly without holding the card number itself.
It is what makes recurring billing possible without every merchant becoming a PCI-scope card vault. The token is meaningless outside the context that issued it, which is the security property.
That same property is the commercial one. A token issued by a platform or app vendor generally cannot be used by anyone else, so whoever holds it holds your ability to bill. Establish portability in writing before you have a subscriber base large enough for it to matter.