Pay with a Like - Locking custom fields in a custom post

Hi. I am interested in implementing the Pay with a Like plugin in a custom post.

One of the custom fields is a private email.
In a bid to prevent spambots from harvesting it and to promote social sharing at the same time, I want to hide the email from a visitor unless they show they are real humans by 'LIKE'-ing my site before it can be revealed.
My Email: [Like our site to view it!]