The key is already programmed to your vehicle it won't reset the program on your car, I change mine about every 3-4 months to insure longer keyless entry distances so you can unlock or lock the car from farther away. Also if your key looks weathered/warned like the plastic looks old you can replace the plastic or the rubber buttons as well from smart madness i believe they have plastic covers and rubber buttons for your smart key.

@@rotaryfd3stt Here's an interesting point I discovered. I swapped out my battery on my smart, and found the key stopped working, It started the car no problem but just wouldn't open or close the doors I put in a brand new tested battery the voltage was correct bang on, I tried everything the key wouldn't work. So I thought perhaps it's the battery? Even though it's brand new so I put in another battery same thing, I decided to try a different brand of battery bingo doors worked perfectly but only after I had pressed the button with the key in the car held on for around 10 seconds. So I tried the other battery again, and even though it was of equal power rating but a cheaper brand the key still didn't work. So the solution I found was to use Panasonic cells over other brands for some reason that's the only brand I have found that actually works in the key fob for opening and closing the doors. The cheap unicell or Tianqiu or Hm power cells simply don't work, I suspect it's the amperage output of the cheap cells over the Panasonic cells, clearly the Panasonic cells put out more power. I think it also makes a difference how long the battery is out of the key as to whether or not you need to press the open door button for 10 seconds while in the car, the 10 second thing works cos I had to do exactly the same thing with my spare key.