There are several instances in Star Trek where a character makes a comment that they no longer use money in the 23rd century – most notably, in Star Trek IV: The Voyage Home when Kirk is explaining to his lunch date why she’s getting stck with the bill.
There are also sevreal other instances of a character or group of characters referring to their pay; Kirk, in “The Doomsday Machine”, telling Scotty, “You’ve just earned your pay for the week”, the weekly poker game on TNG‘s Enterprise-D, and anything involving a Ferrengi.
So, the question is, if they don’t use money, what are they exchanging? Dead fish? That’d be one way to get people to stop asking for payday advance loans.