It's downright impossible if you have privacy settings set to prevent that or keep changing browsers. Did you sign in, work a bit and then sign out and then sign back in on the same browser? Simply bopping from browser to browser will only confuse the situation. Not enabling cookies or having them deleted on exit, will screw things up as well.
There are some e-learning progs that don't require cookies, but apparently, this is not one of them. You can't please everyone all the time.
You seemed to miss the part where we both stated "signed in". He has an account. It keeps track of what he has completed in order for them to ensure he has completed the course. They just need to use that data to tell the program where to start.