There's no specific age that you're no longer allowed to fly as er.
Although the age you're no longer allowed to fly as in being a commercial airline pilot is age 65.
In the United States, commercial airline pilots that are employed by Part 1 certificated airlines must retire at age 65.
Although there's no age limit for private pilots to fly, but private pilots must also be able to maintain their medical certificate and competency.
For pilots the decision to continue flying is often based on medical factors, with cardiovascular conditions and other health issues being the most frequent reasons for being deemed unfit to fly as the pilot ages.
And a pilot's ability to pass their medical checks well as check rides is a more significant factor and indicator on whether they can fly or not instead of their age.
As for flying as a passenger, you can continue flying no matter your age, as long as your health is good enough.
There's even been 90 year old's and older flying without issues.
The most important factor in whether or not you should fly anymore also depends on your physical health and your physical and mental ability to handle the flying journey.
But there's no legal cut off age in which you cannot fly anymore.