I'm a web designer and a client has sent me his copy of Xenforo to customize it. I'm going through the content and found some evidence of a pirated copy. Is there a callback function or something I can check or a way to cross-ref an email address for ownership?
Try running a live version, a lot of illegitimate copies either remove the copyright completely or remove the hyperlink. The best way to find out is check the admin panel and check if the XF copyright exists and if it links to xenforo.com. Of course, not all pirated copies remove it but a lot do. They also annotate parts of the code to say 'nulled by x team w00t visit us now'.