system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek: DS9] I thought the federation got rid of money, how are people buying things in Quark's?

I understand that other races may still use currency, but I see Federation officers buying things in Quark's, gambling, there was even an episode where O'Brien was buying fruit pops on the promenade, but it never showed him paying.

Also, it seems like the replimat is free, and has replicators to make whatever food you might want.  Why would you go to Quark's and pay him to replicate food for you?
gpt
Remember DS9 is a Bajoran station operated with Starfleets assistance. That being said Starfleet personnel stationed abroad are given a stipend in Federation Credits that have a set exchange rate with Bajoran, Ferengi, Cardassian and Klingon currancies on DS9. The replimat isnt free but uses rations that are given to personnel and civilians onboard the station.