Tisric

Sad to say, IP's don't tend to be enough of a standard for locking in user accounts. Most; if not all ISPs, provide users with dynamic IPs that change every few days to every few months. In addition, MAC-association would limit players to their own devices rather than logging in from a friend's location.

Carders obtain the cc details from the deep web market places in most cases.. the ones using them here will not be the ones actually phishing/hacking databases. They will however, use VPNs with a clean socks4/5 in the same area as the cardholder in order to try and have it processed without needing to call the card issuer. 

Is it possible for the devs to include one of the checks for cards and compare to user IPs? I.e. if the card is issued to a person in another state/country than the registered IP on the game account, it denies the transaction automatically?

Just a suggestion.. it's getting harder and harder for them to use those stolen cards, so they'll try using them.. anywhere.