Has there ever been a society that didn't assume that people have free will (and thus, not punished them [directly])?
Could a society exist, that didn't take that assumption of free will?
So far as I know, only fictional societies have existed without some assumption of free will, e.g. Huxley's Brave New World, or Skinner's Walden II.
Could a society exist that didn't take that assumption of free will?
Sure. But only if reality actually conforms to that assumption, that is, if man really does not have free will. In that case, even if a prescribed 'punishment' were seen as inevitable consequences of 'immorality', the repercussions would not be considered as punishment, but perhaps more in the light of training, as in Skinner's Walden II. In such a deterministic worldview, the individual does not have a choice as to whether s/he actually does something, any more than they can escape the consequences of the action. Although theoretically it would be possible to have a society in which no one is punished (directly or indirectly) for their actions, I know of none that conforms to those specifications.
Just because you don't believe in free will doesn't mean you don't believe in punishment. A deterministic society, for example, would still punish those causally responsible for a crime so as to deter future (bad) actions by others who might otherwise do the same thing.
Not believing in free will does not mean you let (for example) murderers roam around and kill as they want without punishing them. It means you don't hold them morally accountable for their actions (you can't "blame" them for their actions in the sense that they "chose" to murder; you can only blame them purely in a causal sense, but you (as a determinist) wouldn't feel vengeful towards them). You still have to punish them (jail, execution, etc), of course, so that they don't keep on murdering people, and so that their unhindered actions don't act as a cause for similar crimes by others in the future.
The assumption of free will is not necessarily for punishment. There have been, and still are, societies that severely limit perception of free will, and yet they seem to dish out the most severe punishment. Namely, societies rules by fundamentalists whose religion assumes omniscient God virtually dispose of free will. The punishment may be performed not necessarily for the purposes of revenge and not for the purposes of prevention; it may be performed simply because God ordered to do so, or so the clerics say.
It can exist I think, but we have to define morality as something independent of free will. Maybe a pragmatic approach; social and moral rules must be defined in a way that anybody who breaks them must be punished, whether He chooses to do it, or whether he has to, anyway he is hurting others. But who will write the rules? I don't know; maybe some meta-society with free will has to exist to make the rules.