If anyone watched the original star trek movies and the first TNG movie "generations" there are multiple instances that show currency of some kind must still exist either on at least a strictly civilian level. Like in the begining of undiscovered country when the crew is entering the briefing and Uhora Mentions that she just bought a boat. Also in Generations we see when picard and kirk are in the nexis kirk enters his home and states he sold it years ago. But there are also points that go to show that money may exist in some form through the early star trek timeline but that it may be totally fazed out by TNG era when replicators are common place..... like in star trek four when kirk goes back in time and realizes that money is still being used.... and has sense enough to barter his glasses for cash, if all forms of money were gone by kirks time he would never have had the sense to do that....it would be like a person from are time going back to say 1890 and using a telegraph for the first time without ever haveing seen or heard of one. it would just never occur to them to use it. I would say that most likely money still existed much as it does today by the time "ENTERPRISE" era started, that money was essentially an extravagence credit system By the "TOS" era, meaning food, shelter and essentials were provided for but anything else you had to work to aqquire, much like the lifestyle of finland is today. and by TNG " the magic and pixey dust system" where all humans live in absolute harmony and can do no wrong with one another, but tends to extend their former problems as a society onto everyone else...but in a flowery sugar coated passive aggressive method. Honestly i think currency exists on the civillian level, there's no other way to keep a planet of 9-11 billion individuals stable provided for... and most importantly Sane! the only way i see a truly free society existing is if the population were incredably small... like say under 10 million. that way the contributions of menial everyday life would serve a worthwile and meaningful purpose....like the aztecs of north america...minus the scrafices and eating of human hearts.