The word or concept I'm after is the system where a user of a service can transfer real money to their account (top-up), receive "credits", use those credits somehow inside the system, and then exchange the credits back to real currency (check-out). These "credits" wouldn't officially be recognized as a currency.
No matter how I try to read credit's wiki definition, the 'provides resources to another party and arranges to repay those resources at a later date' doesn't seem to fit. As told, the purpose of these "credits" for which I try to find a better word for are, to be used as a form of currency inside the service.
This made me think of casino chips, which led me to another interesting contender: exonumia, which unfortunately appears to only be used in the context of physical items.