A "true" communist society like you're talking about has never existed, outside of possibly Israeli kibbutzes and also tribal hunter-gatherer societies before civilization was invented.
In real communist societies like the Soviet Union (which are more accurately labeled "authoritarian socialism"), they need money to control allocation of goods, just like any other modern society. How exactly do you decide how many rolls of toilet paper to give to people? Some people need more than others, so either you have a giant government bureaucracy just to police how much toilet paper people use, how much of every possible type of food to eat, etc., or you just give people money and set prices for stuff, and let them figure it out themselves. These societies were centrally planned, but at some point it's simply impractical to plan everything.
In real communist societies like the Soviet Union (which are more accurately labeled "authoritarian socialism"), they need money to control allocation of goods, just like any other modern society. How exactly do you decide how many rolls of toilet paper to give to people? Some people need more than others, so either you have a giant government bureaucracy just to police how much toilet paper people use, how much of every possible type of food to eat, etc., or you just give people money and set prices for stuff, and let them figure it out themselves. These societies were centrally planned, but at some point it's simply impractical to plan everything.