Cost from entering Pilates subscription as an instructor

Hi!

Since the beginning of this year, I have been working as a Pilates instructor in my secondary occupation, and I have purchased a Pilates class card for myself. This is for professional purposes, of course, so that I can continue to experience the exercises myself and gain inspiration for my own classes. I am searching for the cost category under which I should best enter this (if it is sensible to book it, of course :))? Thank you!