Arsenal should try and "get the best money" for Pierre-Emerick Aubameyang if he does not want to be at the club, according to Ray Parlour.
Aubameyang completed a move to the Emirates Stadium from Borussia Dortmund in January 2018, bringing to an end a prolific five-year spell at Westfalenstadion.
The Gabon international has since managed to prove himself as one of the most deadly strikers in the Premier League, culminating in a Golden Boot win last season.
The 30-year-old has netted 56 goals in 89 appearances across all competitions for the Gunners, and is contracted to remain in north London until the summer of 2021.
However, it has been suggested that Aubameyang may be prepared to cut short his time at the club, having grown frustrated with the team's struggles in the first half of the 2019-20 campaign.
Real Madrid and Barcelona have both been credited with an interest in the Arsenal star ahead of the January transfer window, as have Premier League rivals Manchester United, who are due to arrive at the Emirates for a crucial fixture on New Year's Day.
Parlour acknowledges how important Aubameyang has been in the Gunners' set up over the last couple of years, but doesn't feel that his services should be retained if he refuses to buy into new manager Mikel Arteta's plans.
"It's very hard to keep players," the ex-Arsenal midfielder told Talk Sport. "He's got to be 100 per cent behind [Mikel] Arteta as a manager and really give his all if he's going to stay.
"But if he's 50-50 about whether he wants to stay or go then he's got to make a decision. The players have got more power in this era so the best thing from Arsenal's point of view is if he doesn't want to stay, you try and get the best money for him.
"You try and get as much money as you can, he's 30-years-old now so he's not getting any younger. Are his best days past him? At the moment he's the one who could score you a goal though, he's an instinct player, brilliant player for Arsenal he's been.
"The goal record he's got is unbelievable, but you can't keep unhappy players. We've seen in the past some great players leaving clubs because they don't want to stay there and it won't be any different with Aubameyang and Arsenal."
Aubameyang is likely to keep his place in Arteta's starting XI when Arsenal play host to United, where he will be looking to add to his tally of 13 Premier League goals this season.
The Gunners are still awaiting their first win under Arteta, who has overseen a 1-1 draw at Bournemouth and a 2-1 home defeat to Chelsea in his first two games at the helm.
Arsenal must beat United to keep their faint hopes of a top-four finish alive, before turning their attention to an FA Cup third-round tie against Leeds United on January 6.