There are three forms of cashless society that I can think of. One if where everyone produces goods or services and barters with others to get what they need. The problem with this is that if I am a mechanic and need bread, but the baker does not need a mechanic right now, I have to first find someone that has something to offer the baker and also needs a mechanic. I can't just go get bread. This could potentially be eased with a coop concept where a mechanic, a baker, and and others all come together. The coop then connects everyone's needs to create trade triangles or such.
The second possible system would be a communist society where everything goes to the community and is then redistributed by the community. The challenge with this Is that it becomes difficult to distribute goods equitably while still encouraging maximum production.
The third method is to simply have everyone give everyone else what they have that others need, but again, there is no motivation to work hard and reach optimum production levels.
A cashless society, such as in Star Trek, really requires a surplus economy where there is no limit to what people can have or requires a very well thought out and managed system that rewards people for doing a good job and that fairly distributes the goods. I will poing out, however, that even Star Trek couldn't conceive of a cashless society. Ona a ship where every one is following orders, has uniform lodging provided, has replicators that can provide anything people want, and a captain that oversees any requests for anything outside that, including a request for a new job. Once they mixed civilians in including on Earth or on DS9, once they introduced interaction with those outside the Federationespecially the Ferangi, and once they introduced conditions where replicated items weren't completely unlimited such as on Voyager, some sort of currency or spending allowance had to be introduced in all those cases.
Ultimately what currency provides is the ability to select your priorities of what you want. Unless there is so much abundance that everyone can have everything they could ever want (and I am not saying this isn't someday possible, but right now it isn't the case) than people have to choose what they do and don't want. You can't just give everyone the same because different people want different things. You could potentially have all money issued by the government and let people spend that money on what they need or want, and have everything produced go to the government to sell so that you can ensure equality and make sure everyone gets enough to live on, but you would still need to somehow reward people for producing more difficult products or services or producing better quantity or quality. People are naturally lazy and if there is no potential for reward for going above and beyond, they will do the least that they can get away with. People don't work overtime for free, they don't innovate for free, and they don't work harder for free. They do so because they have something personal to gain from it.
In the end, though, even if you were to go to a society with no currency, it would be complicated and limiting, and I don't really see any advantage to it. There is no cashless economic system that can't be also run with a currency and wouldn't be simpler and more efficient to manage with a currency. The Star Trek ideal that many people fantasize about talks about how there is no money or greed, but the truth is the key to that isn't the lack of currency, it's the lack of scarcity. Scarcity is still a part of our economy no matter what economic system we use. In Star Trek they have no money or greed because everyone gets everything they want, and everyone is forced to provide their services at an equitable level or risk court martial, and are encouraged to function at their best to earn promotion.
Long story short, a cashless society might be a dream of many who have watched Star Trek or who have had money problems, but at the end of the day getting rid of currency isn't as practical as it seems and wouldn't solve the problems we like to think it would anyway. Instead of trying to dream up a way to eradicate what has become a symbol for our problems, let's instead focus our attention on developing or identifying an economic system that will actually help to solved those problems.
