Hi ! Sorry About Bad English

I have a so-called "MP3 site" that will feature a collection of
audio and video clips. Obviously, bandwidth is an important factor
I have one great script for that PHPAtm Anyway, what I'd like to do is setup some kind of security feature that will only allow a registered person to download
certain clips only once.
I pay for it. I need that script PLEASEEE HELPPP
Best Wishes From Austria