The Belgium international was installed as first-choice keeper when he returned to the Blues in 2014 following a three-season loan spell at Atletico Madrid.
In the 2014-15 campaign, Courtois picked up a Premier League winners' medal, but Chelsea will end this season without silverware as they are 10 points off the top four and are out of the FA Cup and Champions League.
Courtois does not come to the end of his contract until 2019, but he has not ruled out leaving the Blues in the near future.
According to FourFourTwo, when asked if he will stay at the club beyond this season, the shot-stopper said: "I do not say yes, I do not say no. I do not know. I still have three years on my contract. We must see what Chelsea want.
"It is true that [this season] has changed me. Until now I had always won a trophy every season. We hope that next season will be better."
Courtois spent a large chunk of the season out injured, but has since resumed his number one role.