YMz android app, does it work?

I bought the app, admittedly haven't used it a great deal. Went to use it yeserday...get a message the app isn't registered or something, and a prompt to "buy it!" Like all these messages, initial reaction is to doubt one's own sanity and buy it again, second reaction, is this app malicious or a con? Does it work?

Could you post the exact error message you receive?