I bought a 2005 STS and it came with one key. That worked great, remote start worked, everything worked. Then I managed to find another fob at the junk yard. Using the physical key, I managed to pair that fob with the car, but the car said that that was now fob number 3. The problem with being either key number 3 or 4 is that they won't activate some of the features of the car, like remote start. I made sure to enable remote start, and save the settings to the driver selection with the key (key #3). To solve this issue I had to go through the 30 min process to delete all previous keys from the car, and then reprogram my current keys as key 1 and 2. Now remote start works correctly on the "new" key. I hope this helps someone else who is confused as to why their key just doesn't use all the features of the car.