How can I change the course's price to Subscription?

Hi,

I'm currently setting up an E-Learning website using CoursePress, the customer will register to a subscription through Membermouse, the problem is that while setting the Course (in CoursePress) it asks only if is PAID (Fixed price, like a product) or FREE, I need an option that says ¨You Have to Subscribe to a membership to have access¨ or the other option would be to change
PRICE: FREE to
PRICE: SUBSCRIPTION or MEMBERSHIP

I attached some screenshots so you can understand better what I need.

Thanks for your help.

Philipe