Hi Roger
The tracking of eLearning online, I believe, is done by a Learning Management System (LMS). These have the features you are describing, though I'm not sure about assuring payment (though I don't see why not). LMS's sometimes are part of an eLearning software suite, sometimes standalone. Maybe expensive. They are standardized using AICC or (more currently) SCORM. I hope others with LMS experience can guide you further.
One innovative way to assure registration and payment is to offer the eLearning materials at no cost, but set up a payment if the viewer wants verification that they took the course and/or a continuing education certificate. This can be set up to issue if a certain score is reached on a quiz based on the materials, registration and payment. This will only apply to certain types of eLearning for which a viewer needs verification.
I hope this give you some leads.
Contact me directly at
swartel@nycap.rr.com if you would like some more info about LMS or the continuing ed feature mentioned, as I've set up the latter.
Kind Regards,
Stephen