Investigators will inspect whether the pilot who disappeared with Cardiff City's Emiliano Sala had the correct licence.
Pilot, David Ibbotson, was an experienced flyer who held a private pilot's licence and passed a medical exam as recently as November according to Federal Aviation Administration records.
The aircraft was registered in the US so fell under the States' regulations.
US law says private pilots cannot make a profit by carrying passengers.
A spokesman for the Air Accident Investigation Branch said it has opened a probe and confirmed they will investigate all aspects of the flight including licensing.
The search for the missing plane was formally called off on Thursday after rescuers said chances of finding the missing pair alive are "remote."
Guernsey's Harbour Master, David Barker said it was a difficult decision but he was "absolutely confident" no more could be done.
Emiliano Sala's sister Romina, who arrived in Cardiff on Thursday, told a press conference she feels "they are alive.. that they are well" and pleaded for the search to continue.
Sala's former club FC Nantes backed Ms Sala's calls for the search to resume saying the hunt for the plane "can not stop."
Lionel Messi and Diego Maradona have also joined calls to resume the search for the missing plane.
Barcelona star Messi posted on his Instagram story, said: "As long as there are still possibilities, a hint of hope, we ask you please continue to look for Emiliano.
"I send all my strength and support to his family and friends. #PrayforSala."
1986 World Cup winner Maradona, also posted on Instagram pleading for the search to continue, with the message: "Hope never dies."
Manchester City forward Sergio Aguero, used the social media hashtag #NoDejenDeBuscar - "do not stop searching".
Cardiff signed 28-year-old Sala for a club-record £15million to bolster their attack and he had been due to start training on Tuesday.
Rescue teams have scanned around 1,700 square miles and examined mobile phone data and satellite imagery but found no trace of the aircraft.
Three planes and five helicopters racked up 80 hours combined flying time looking for the plane, working alongside two lifeboats and other passing ships.