Ideally, you wouldn’t need to buy, if they don’t need to make money to survive. They would provide entertainment options to the public just as farmers provide their produce and electricians provide their services.

Across societies, that’s where it gets more difficult, particularly if the others don’t have that same system. The other comment already suggested a communal pool of money used to trade with other communes, which makes sense. A given commune probably can’t produce all it needs or wants locally, and money in some form is a valuable “lubricant” for trade where payment in kind (goods and services) or promises is impractical (because you might not have goods or services they need or might not be able to fulfill your promise).

So if buying a game made somewhere else and you can’t come to some other agreement (like helping the developers fix their plumbing in exchange for a copy), I suppose there would have to be a mechanism to order a copy through that communal pool. The game should probably also become communal property if your own livelihood is supplied by the community. If it doesn’t allow multiple people to play with the same copy at once, purchasing more copies may be necessary, but maybe you can also arrange a way to take turns.