I'm not super great with expressing emotions so I don't really thank her out loud, although I hope she can tell by the way I treat her how grateful I am for her...
I do remember thanking her once when she went out of her way to schedule a session for me out of her regular hours.
With my old T, during our last session, I couldn't even thank her lol, I said "I don't really have the words to express how grateful I am..." and I kinda paused and she smiled and said "it's okay, you don't need words" so I think she understood