If you apply the maximum allowed voltage to your motor and run it at or over its power rating and it has no cooling then it will curl up and die soon. Read the fine print about heat and how to cool it in its datasheet.
My electric radio controlled model airplanes have a very small motor that produces a lot of power. Flying, the motor has forced air cooling but it gets very hot and the manufacturer recommends full power for short durations and letting it cool down before it flies again. Of course, PWM is used for its speed control.