You need to answer the more fundamental question of whether in-app-purchase is allowed for this at all.
If in-app-purchase is allowed, Apple takes 30% (or 15%) of the total value of the transaction, as well as any applicable taxes. If in-app-purchase is not allowed, you need to provide your own payment processing and Apple take nothing.
As to whether in-app-purchase is allowed, the primary question is whether the purchased content is delivered in the app. You talk about "shows" and "lectures", but I take it that these are actually streamed videos; are these presented in your app? I'm not totally familiar with the current rules in this case; I think there are some relatively new exceptions for one-to-one consultations.