A student once told me that token economics was a type of economics created by J.R.R. Tolkien...Yes, the same guy who wrote Lord of the Rings. Sorry, but token economics is a behavioral approached used to change the behavior of patients with severe psychological disorders (although it can be used with anyone, this is often how we talk about it in psychology). Patients in a hospital are rewarded with tokens for exhibiting and performing desired behaviors. The tokens are then used to purchase things that the patient wants.
For example, extra time watching TV or playing a video game. In this way, patients learn to "modify" their "behavior" in order to receive tokens.