You are confusing socialism and communism. Communism is where money is gone. Socialism is where money is very well present, but the capital, the means of production and the economic planning is controlled by the state. The workers still can get paid (and some may even have certain freedom in where to work, though that tends to shrink very fast as central planning is not possible if you can't force people to work where you want them for salary that you want to pay them) and still can buy stuff (provided the central planners thought in advance of producing this stuff in enough quantity), but the overall control of the economic processes rests firmly in the hands of the state.