Anybody know where I'd find my subscription number?

...subscription number is about second from last item. (It is labeled.)

...then "My Reviews" and then click on one of your reviews to see your member ID.  But it is practically useless - it's just for TER bookkeeping.  If a provider is asking you for your TER ID, she means your handle - Otilo2 - not your ID number.

if you ask to be notified when any of your favorites get a new review, your ID number will be in the email msg.  Other than that, you really don't need it anyway.  I have never used my ID number for anything.  Providers' ID's are needed, but not ours.

...is to cancel his membership. The cancellation form asks for your subscription number.