I knew I was done with therapy with my first therapist when she wasn't helping me anymore. We couldn't go further. I think that's a good landmark, at least for me. Later I went to see a different therapist and I am still with him, several years later. He is still helping me, I am still learning, so I stay. I also went to see a family therapist with my daughter and after about a year, we stopped. We really weren't going further and we had learned some things and it seemed like enough. We were ready to take what we learned and proceed all on our own. I feel what's common in all three cases is the sense of still growing and learning vs. "we've learned all we can or all that we're willing to from this person."