A US judge on Friday sentenced the owner and operator of iBackups.net to 87 months in prison, the longest sentence ever given for software piracy, according to a software trade group.

Nathan Peterson, of California, also forfeited nearly all of his assets to the US District Court for the Eastern District of Virginia in Alexandria, and he agreed to pay more than $5.4m (about £2.9m) in restitution, the SIIA (Software and Information Industry Association) said. Peterson pleaded guilty to two counts of criminal copyright infringement in December.

At that time, the US DoJ (Department of Justice) called iBackups.net "the largest for-profit software piracy site ever shut down by law enforcement." The website illegally sold software that would have been worth $20m (£10.7m) on the retail market, the DoJ said.

Peterson will begin paying off the remaining $5m (£2.7m) in damages 60 days after his release from prison, at a rate of $200 (£107) per month.

In criminal piracy cases, the average damages resulting from pirated software are just over $9m (£4.8m), or less than half of the $20m caused by iBackups, SIIA said. The $5.4m Peterson agreed to pay in restitution is eight times the average fine of $659,000 (£353,000), according to a SIIA study tracking FBI cases on software piracy reported since 2000.

Peterson's site used Google text ads to find customers, SIIA said. Buyers should be aware of the possibility that software being sold through text ads might not be legal, the trade group said.

Neither the prosecutor nor Peterson's attorney immediately returned calls seeking comment.