When data is paid for, transaction information is stored on the Network in ‘spends’. These contain the transaction plus all its inputs and outputs.
To audit and check against possible double-spend, clients can trace a spend's history and locate all subsequent spends recursively to build a directed acyclic graph (DAG).
Spends could be for Data Payments, or direct transfers between users, or 3rd parties. For the purposes of everyday payments, users need only check the parents of each spend. However, transactions can be traced all the way back to the Genesis or emission event using the DAG, if required. You can audit the entire token supply in this way, should you choose to.