Depends on the #booze and the #party.
Discussion
We can try some examples:
Party at your friend's house, you have a few beers left over
Party at your friend's house, you have half a bottle of wine left over
Party at your friend's house, you have half a bottle of whiskey left over
For me the deciding factor is whether or not they would finish it if I left it. My good friends, I know the answer typically. Acquaintances get to keep whatever is left. Wine will definitely get finished before I leave so I never have to worry about that.
That was not a predictable answer, I like it, your logic is sound.