Messi has a contract at Camp Nou until 2021 but a report in El Pais on Thursday revealed there's a clause which allows him to leave at the end of each season if he so wishes. The Argentina international would just have to communicate his desire to move on before the end of May.
Carles Puyol, Xavi Hernandez and Andres Iniesta all signed similar deals with Barca in the final years of their time at the club, too.
Pique is aware of the existence of the clause but insists he is not worried about Messi quitting Barcelona any time soon.
"I already knew Messi is able to leave for free at the end of each season," the defender told Cadena Ser. "But we all know the commitment Leo has to Barca and it doesn't worry me at all. He's earned the right to be able to choose what he does with his future after everything he's given the club."
Messi agreed his existing terms in 2017, eventually signing the contract in November after Barcelona had announced an agreement was in place in June. The delay in getting him to sign almost saw him move into the last six months of his deal, when he would have been free to negotiate with other clubs.
Despite it being less than two years since Messi signed that contract, Josep Maria Bartomeu is already working on his next new contract, which could be his last with the club -- he will turn 33 next summer and will be 34 when his current terms expire in 2022, the year of the next World Cup in Qatar.
The Barca president told ESPN FC in April that he wants to keep Messi at the club "forever" and that he plans to sit down with him and his representatives to discuss extending his deal.
Since signing his first professional contract in 2004, Messi has been handed eight renewals by the Catalan club, with his release clause rising to €700 million in the process.
That clause carries less weight with the revelation that Barcelona will not stand in Messi's way if he wants to leave, but sources have told ESPN FC that there's no panic about the possibility of him taking on a new challenge in the short-term.
Messi has always maintained that he would like to end his career "at home" in Barcelona, although he has also suggested he would be open to a stint at boyhood club Newell's Old Boys in his native Rosario before he finally hangs up his boots.
With 603 goals, Messi is the top scorer in Barcelona's history by a distance. He has also made 687 appearances for the club, a figure only bettered by Xavi (767).
He's yet to play for the Spanish champions this season, though, due to a calf injury. He's taking advantage of the current international break to do recovery work with the hope of returning to action next weekend against Valencia in La Liga.
His last competitive game was for Argentina against Chile in the Copa America at the beginning of July.