An amp meter/watt meter is not just nice to have, I feel it's absolutely essential for someone who flies electrics. The amps that the motor draws from the battery will tell you if the motor is overloaded. Using a prop that is too large will overload your motor. Substituting a motor with a higher Kv rating can also result in an overload if you don't switch to a smaller prop or use fewer cells.
Abused electric motors die fast.
Unabused electric motors will last almost forever, especially the ball bearing brushless motors.