A gateway encryption service is used to ensure consistent, source independent tokenization for payment accounts and synchronizing payment account information with merchants. A consistent, evergreen merchant-facing token is generated and used for each payment account for the merchant, ensuring that regardless of the payment method used by the customer (e.g., plastic card point-of-sale, pay wallet, saved card information) for the same underlying account, the merchant has a single token. Further, if the account number for the underlying payment account changes (e.g., the card expires or is stolen) the merchant-facing token remains consistent. The evergreen token ensures that the system functions more efficiently, saving resources in processing and storage and ensuring less network traffic for failed transactions. The system further implements encryption and security despite the consistent tokenization, further saving resources.