I would imagine that a therapist will respect your decision to stop. However if they feel you still need therapy, they will be honest about that. Just cancelling and not going back for a final "closure" session seems a shame. Quite often you can get lots from your last session. Usually the door is left open for you to return if you need to and they will wish you well.

The thing you have to ask yourself is even tho you may not be getting anything from your sessions, do you still need therapy?