Robinson fully expected the show to be as successful in the long run in America as in the UK.
The Anne Robinson hosted show pulled in an audience of 14.1 million households on Monday night, in its second week on American television.
That compares with 15, 14 and 17.5 million on the first three nights of its opening run, which easily beat the other networks' shows.
"We are delighted the show has been such a hit for NBC and has become an important part of their summer schedule," said Colin Jarvis, BBC Worldwide's director of programmes and operations.
The quiz was originally scheduled to run for 13 episodes but the ratings success of the show has convinced NBC bosses to extend the programme's life.
Critics and audiences have been split over Robinson's rude style - but she and her show have attracted the ratings that will please network NBC.
On its first two nights, on Monday and Tuesday, it was the second most-watched show in the country behind popular sitcoms Frasier and Everybody Loves Raymond.
Dominatrix
There have been reports that the show may go head-to-head with the other successful British exported quiz, Who Wants to be a Millionaire?
The US version of the show regularly pulls in 19 million households for ABC, making it the US's most popular show.
Robinson fully expected the show to be as successful in the long run in America as in the UK.
The New York Post reported on Wednesday that she is planning to buy a house in New York.
"Because of the success we will be spending a lot more time in America and so we are having to find somewhere there," her husband and manager John Penrose told the newspaper.
NBC have played on Anne's dominatrix image, billing her as TV's rudest woman.
Antidote
The New York Post newspaper devoted a front page last week to Robinson, under the headline "Host from Hell".
Viewers have described her as everything from "sophisticated" to the new "bogeyman".
But Mr Jarvis said: "It is great to see Anne's unique style and wit has travelled so well across the Atlantic."
Ms Robinson will have to make further trips to the US to record the new shows
A spokeswoman said she did not believe it would cause too many scheduling problems.
"Anne will fit it in. She is splitting her time between the US and UK to record the shows," she said.
She added: "She has recorded about eight of the first 13 shows so far and will be going back to film the remainder."
It is thought the 13 extra shows will follow straight on from the current run on US TV.