Maybe you can help us. I have been searching, with no luck. Some of our students are going to pay all the cost of the course at the beginning. And some of our students are going to pay in a monthly basis. How could I grant access to the different sections or units sequentially, as they pay?. I don't want to grant access to the whole course before they pay completely because I cannot be sure that they will keep paying once the "take" what they need. Take into account that the students are going to enroll in different moments, the course does not have a beginning date, I mean.