I've had mine for almost 2 years (23 months) and both are still going strong. The buttons are hardly ever pressed though as they are always in my pocket and my wife's is always in her purse.

 

Isn' the car and the keyfab communicating while it's in or near the sensor field? So they are sending signals even though it is in your pocket. That's why the battery is draining. It send a low signal to the car. So I was told. Unless the person had no idea.

 

^^ That is true - the red "key" indicator light flashes when the key is around the car and it has to involve a signal from the fob, and thus drain the battery.