Thank you for your attention to this matter. I am creating a course of 48 topics (in Moodle 3.2) in which each student can enroll at different times and can visualize part of the material according to their mode of payment. That is, if you pay the entire course, you can access to all the units, topics, resources…, but if you choose the monthly payment method, I have to activate 4 topics each month, or if you choose half-yearly payment, 24 topics first and 24 later. 

Each student can choose how to pay, so I don’t know how to control all the content of the course depending on what is paid and when. 

 Thanks in advance for your help!!