Create a time sensitive script/code that allows people to only watch a video three times

I am wanting to upload an elearning video to my website, but only want each person to watch it a maximum of three times ( this will stop people passing on or potentially sharing usernames and passwords). I need someone to help me create a script that will do this. The two options I'm thinking about include: a. A webpage that expires in 12 hours after someone has started to first login. b. A webpage which allows a unique user to only access it three times ( after which it expires). I'm quite open to the way this is done and what platform to use. Also, there should be done automatically after purchasing a product from a shopping cart. If you wish, please send me a reply so we can enter a dialogue and discuss this further. PAUL