Having a closing session with client who terminates?

So I'm currently in my practicum. While I've had a client or maybe 2 that I've seen once so far and then they disappeared, it hasn't been until now that I've had one where I've seen for a handful of sessions that has now called me saying they wanted to end therapy.

So I'm curious for any more seasoned therapist out there -- do you do a closing therapy session with your clients? And if so, about how many sessions do you usually have with them for you to determine that that's in the best interest for the therapeutic relationship? What do you go over in the closing session?