[Milford8000]

I recently obtained a VPN and when I go to download from some of the Uploadship links, when the fast downloader link is dead, the link says it is there, but it says to use your real IP or purchase an account. It gave me this message on the screen,
" This IP ( xxx.xxx.xxx.xxx ) Can't Use Free Download Feature With Us ( Please Use your Real IP For Free Download Or Upgrade ) ! And then it would only show purchase information, no links or capcha. That makes it sound like to me that they want to trace who and what is being downloaded and possibly trace who it is. If they insist on the real IP and not a VPN, I would recommend not using that site to upload to and download from. Just for your own security. Your call.

[Disk4mat]

I highly doubt it's for tracking, I suspect it's because a lot of users who use VPNs don't get served ads. Essentially it's the same as filehosts not allowing users who have adblockers enabled.