I've never had any after-the-session-period relationship with any T. All of them had helped me to develop real world relationships, and I pursued those.
I have, in some cases, called former Ts to update them & thank them for especially helpful progress we made together. They've all been glad to hear from me, but it's remained professional--no follow up contact.
This has worked for me. I like thanking these special professionals in my past and letting them know some results of their hard work ... especially the good stuff.
Roadie