nk497 writes "A single licence for Avast security software has been used by 774,651 people after it went viral on a file-sharing site. Avast noticed that a license for its paid-for security software, sold to a 14-user firm in Arizona, was being distributed online. Rather than shut down the piracy, the company decided to see how far the software would spread — it's since popped up in 200 countries, including the Vatican City. Now, the company is turning it into a marketing opportunity, with a pop-up encouraging users of the pirated copy to download a legal copy of the free or paid-for version. Avast isn't sure how many pirates have gone legal, but said some have made the switch."