Kids need it constantly reinforced that nothing they did not pay out of their own pocket is theirs to keep unconditionally. It is theirs to use until a parent deems it otherwise.
My husband used to urge me to say “No” more often to our children...just because. He felt they needed to get used to hearing it after all, life says no quite a bit, look at that Santa Barbara killer, couldn’t take no either. It is a modern phenomenon that parents are afraid of their children, even at three, maybe especially at three as three year olds can be horrid little bullies. We’ve been told for so long we have to “understand them” and “give them choices” (oh and they have to like all choices offered) and not spank them, etc. It’s no wonder we’re messed up.