My P4 has more than a hundred hours on it and the motors are working fine. The Inspire has a little over 90 hours and no motor problems, just one prop problem but replaced all four props.
Hover your drone three to five minutes close to the ground, land and do a smell and heat test. Pick up an inexpensive digital temperature gun and check each motor for excessive heat. If a motor is running considerably hotter than the others, time for new motor.