The new software includes cookie-based features for limiting concurrent logins. Traditionally, says Flicks, concurrent logins were identified by monitoring the user names and originating IP addresses of Web site visitors. But, because some proxy hosts revolve IP addresses mid-session, legitimate users often appear to be using more than one IP address.

According to Kevin Flick, CEO of Flicks Software, password sharing is a major problem for the online subscription industry, and its effects go deep into the business. "One person will purchase a subscription to a Web site," he says, "then email their friends - or even worse, post online - the user name and password. Victimized companies see the perceived value of their online content plummet, and their bandwidth charges skyrocket. The company's business model eventually fails, and its Web host loses a customer."