According to Vince Steckler, Avast's CEO, just 217 users of the license key are legitimate, and, as with the pirated version of the Vatican's business licence which his firm reported late last year, the numbers have built up steadily over a relatively short period of time.
The big jump in numbers, he says, came just after his firm shut down another pirated licence in December.
"We had been wondering how long it would take the pirates to find another license. It surprised even us that in only three months, around 750,000 users of the previous pirated license had essentially shifted to this law association's license", he said.
From its start in Arizona, Avast says that the licence is now being used by pirate users in 218 countries and territories.
"It is quite interesting that both of our massively pirated licenses came from Arizona", said Steckler, who added that this latest license piracy incident is different from earlier pirates in that the take-up was a lot faster.
The license, says the firm, spread to three-quarters of a million users in nine months after it was originally sold. Almost all of these users came in the last three months.
As with the Vatican pirated licence reported last December, Steckler says that he plans to offer the pirate users a chance to go legitimate.
"We don't want to be suing or employing lawyers on this", he said, adding that, as before, the plan is to inform, then convert or switch.
"We will see what happens this time", he noted.