Any idea how to restrict this to "1 copy paid for, 1 copy used" and not being shared to friends? I have no problem understanding what you are trying to say here but it just isnt possible.
Why would you want such a restriction ?
If his friends are fans, they already have (or will) bought it. If they are not, they wouldn't have and won't buy it. By not restricting it, you gain a new user, maybe a new developer, and you don't loose one.