In DS9's "Prodigal Daughter", Morica Bilby is asking money of the Tigan family. As the Federation gave up on the concept of currency, does this imply that Trill is not a Federation world, hence its currency?
There's an implication -- or perhaps an easily-made inference, since it may have been unintended -- that while the "official" Federation economy is not just cashless but truly non-monetary, there is a less official, grey-market economy that is not only monetary, but has fallen back on "hard" currency that cannot be replicated, like gold-pressed latinum. This grey market almost has to be tolerated in order to interact and trade with non-Federation members like the Ferengi and, for that matter, Bajor, but it also opens the door to situations like that in "Prodigal Daughter", where individuals who are already somewhat outside the system can think in terms of cold, hard, untraceable cash.
It can similarly be inferred that some kind of exchange system has been set up with Quark, whereby the Federation periodically dumps latinum in his lap on behalf of Starfleet members and other Federation citizens patronizing his establishment. We never actually see any Starfleet member pay in latinum, but Quark periodically makes comments that suggest he is keeping a tab per person, which means someone is paying that tab in the only currency Quark would ever accept.
Bashir: But the authorities on New Sidney weren't very cooperative...
Bashir: And since it isn't a Federation world, Starfleet doesn't have any jurisdiction.
Sisko: So he decided to turn into a one man police force...
This doesn't imply anything about Trill, as there are also humans living in non-Federation worlds who make money either to survive or simply because they want to.
New Sidney is likely located somewhere towards the Borderland (given the Orion Syndicate's presence there), far away from the heart of the Federation and its values and resources. It's an independent world that is inhabited by many races interested in its local resources and doing business there. As such, it makes sense that the local economy still uses money and explains why the Orion Syndicate would also operate there.
Also, a moneyless economy doesn't seem to be a requisite for joining the Federation. Bajor clearly hasn't evolved past a capitalist economy when it was first granted membership.