The Zeus bot client is perhaps the most popular and pervasive piece of malware of its kind right now. It has gone through a number of revisions and upgrades in recent months. The latest release, version 1.3.4.x, added this functionality to prevent rivals from selling pirated versions of the attack kit. This represents a significant leap in the sophistication and professionalism of malware development, researchers say. The newest release of Zeus is selling for $3,000 to $4,000 right now in private sales.
Source: https://threatpost.com/zeus-trojan-now-has-hardware-licensing-scheme-031710/73698/