For me, closure with my former T was dedicating our last session to wrapping things up we had talked about previously, then she kind of recapped the work we did ("when you first came in, you were x but I feel as if I have watched you grow as we did y together") and kind of told me how she viewed our therapy from her perspective, which was nice to hear since she was a pretty blank slate throughout therapy. Then she ended by giving me the name of a new T she thought I would get on well with, and told me about her future plans (opening private practice in a few years) and said I could come see her again when she does, if I wanted.