I am new and want to know if a customer can download a text file based on there on line account. I want to know if I could have them log on and then, if there account authorizes it, they could down load a text file, the text files, would be in sequence and I would be loading the file based on the customers purchase of a license string. If not, it would send me an email telling me the account has run out of the license, and would let them know I was being contacted and would get with them to purchase additional license.

Your going to want a php login setup. This will allow you to set $_SESSION variables based on the user so you can return dynamic data based on who they are.