Every place that is inhabited will eventually be governed one way or another. Settlements of interstellar polities are no different. But how exactly. Probaly our current systems wouldn't really work since they are based on planet surface control, but a spacebourne community could have settlements on orbit, on other planetary bodies. They could also have settlements floating on seas and settlements below the seas. They could also have settlements deep in the planetary bodie's crust. Individual settlements perhaps could be somehow divided into our current style administrative divisions. But stuff gets tricky when we start to put orbiting bodies into administrative divisions. They don't have clear borders since they tend to move around quite large distances.

I could see star systems fitting into our current administrative division style. They can be considered to be standing still in relation to each other according to human perseption of time.

At higher level I think that people would adopt some sort of a vassal-liege system, where vassals are relatively independent. But planet surface could be divided with the convendtional methods.