Create product registration page

Site URL: http://www.care4acause.com

Hello, I created a company called CARE for a Cause where I sell environmental awareness starter kits that come with a virtual guidebook. At the moment, customers receive a notecard in their package with a general passcode to access the locked page where the books are embedded. Everyone recieved the same passcode but I want a way for customers to register their kits with a unique passcode created just for them as opposed to a password protected page so that it is more secure and cannot be accessed by a third party. I will definitely have to get the commerce plan so that people can create an account and then from there I could have a page with their "library" that only they can access. Hope this makes sense. This is the best solution that I have come up with but if anyone has any other suggestions that I could try before having to hire someone to build on the back end i would appreciate the feedback. Thanks!