DLC Dowload for big packs

Hello everyone!
I’m making a BIG project that contains a lot of footage and I need buyers to connect to another server in order to download it.
There is some way to ensure that people who dowload that files are really buyers and do not have the links by another way?
I don’t know yet if it’s gonna be rejected so I can’t make any great investment. I would only upload to Google Drive.
I know CINEPUNCH has this option, but my files contains alpha channel and Vimeo would be not valid for me.

Thank you very much!

You can use the envato api to check for a valid purchase code on your own website, and only if one is provided let the user download the software.

Does need your own webspace and some coding skills, though.

Thank you very much for your reply! Actually it consist on a set of footage.