Reference transaction are payment transactions that utilize a transaction ID from a previously authorized transaction to process a subsequent payment. The use of reference transactions or tokenization reduces the PCI scope for merchants who are concerned about storing credit card data.
PayPal has two types of reference transactions: credit card reference transactions and billing agreement IDs (BAIDs).
A reference transaction must have occurred within the past 730 days because the ID may not be available after two years.
Credit Card Retokenization
Retokenization involves creating a $1.00 transaction and a voided negative $1.00 transaction. Since organizations are charged a fee to retokenize credit cards, the process should give you several options so you only retokenize the necessary credit cards.
Organizations must have their credit card payment gateway defined to allow reference transactions.