Whenever there's a storyline with quark, they talk about money/latinum.

I remember in one of the next gen episodes that there was discussion about money and Picard said something about how they've moved away from money.

So do Starfleet get paid now?

Update: thank you for the quick responses. From what I'm gathering the tldr is that the following is the answer

• Ferengi love for money/not being a post scarcity society by design
• Bajorans being so near their slavery times and not post scarcity yet
• Quark creating an atmosphere of camaraderie/gambling/upgraded replicators/actual food

All this requires some form of currency.