Nice observation. Yes, it means that the action concluded.
I've just been touring Europe. Now it's time to settle into life at home again.
Sometimes people will say "finished" or "stopped" instead of "been" to reinforce the clarity, but this is not necessary to the meaning.
He's just finished making supper.
However, there are different meanings of "just". The one you intend means "recently finished", but as you probably know, there's also the meaning "only".
What are you doing up so late?
I've just been editing my essay.
Here the person means that this is all they've been doing, nothing more — and they're not necessarily finished!
The intonation is not always enough to distinguish these two, so you can't be quite sure without thinking about context or asking for clarification.