Reload issue

I am up against a deadline. I have spent over 20 hours and and can't come up with a solution. I have created an autism awareness training program for first responders. The training is free, unless you need continuing education hours. Then it sends you to PayPal for a $10.00 donation. PayPal sends you back to a slide with an embedded google form that lets you enter your required info and when you submit it, it emails you a completed CE certificate. That all works great. Problem is, they can just keep reloading the page and keep printing certificates. I can disable that feature in player, but then the person training would have to restart the 3 hours of training each time, instead of resuming where they left off.  Help!!! is there a solution??? I have to debut this Wednesday at a fire conference in Nashville.