The first key carried alone adds responsibility to an ordinary pocket.

A key handed over is a small ceremony disguised as an object. It means somebody believes you will lock up, remember it, come home at a sensible hour, and it means that from now on your absence and presence are yours to manage. Nothing in the metal says any of this. All of it is carried anyway.

If you have handed a key to a younger person, say what it means rather than assuming it is obvious. If you have just been given one, notice the shift. Freedom and responsibility usually arrive in the same pocket, at the same moment.