Social signals referral required to access free content?

[Oimachi2]

I have some free resources available (Canada customs documents) and visitors download them like crazy and use my bandwidth...however, I get no credit for it...

How could I make something to ask for a social signal BEFORE they get their free download?

Something that would say:

"In order to get this free dowload, please give us a Google+ or Facebook Like"

Thanks

[martinibuster]

Take a look at the Social Locker Plugin for Wordpress. It's fool-proof. Non-fools can still get the content by peeking at the source code (at least the implementation I saw the other day).
[sociallocker.org...]