The Portugal international has been linked with Paris Saint-Germain and Manchester United in recent years but has repeatedly rejected speculation he could quit the Bernabeu.
However, when asked about his future as he was presented with the Pichichi prize for scoring the most goals in La Liga last season, he revealed he may not see out his career with Madrid.
"I have been in Spain six years. I was also at Manchester United for six years and that was a great experience, a great championship, but for me this is the best league in the world," Ronaldo said to Marca. "It's a privilege to be here.
"I want to be here for a couple more years and then we'll see. That's the duration of my contract and I want to give my all in that time."
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The Madrid star, who was voted second in the Ballon d'Or earlier in 2016, also paid tribute to his support system at the Bernabeu as well as the club's supporters.
"I dedicate this award to the team, to the coaches, the staff and everyone at Madrid," he enthused. "Without them, I wouldn't have been able to score so many goals last season.
"Let's hope the fans keep supporting as they have been. They are spectacular. We will give everything on the pitch to try to win trophies and the Champions League once again."