I've had sessions recorded as part of research on group work. But i've never actively recorded a session between myself and a professional - i have no desire too and even if i did what would be the point? My experiences are usually bad and i don't need to be reminded of them.
I don't know if your post relates to something you've done personally but if this something you're doing/have done without the express consent of the other person - please be very careful. No one can tell you what to do but i would hate for the relationship between yourself and T to become more complicated. Gentle hugs