My 2011 X5 simply doesn't remember which key is whose, even with the box checked. If you look around, there are youtube videos of dealers demoing how it's supposed to work, and there are forum posts of folks taking their cars to the dealer countless times and it never getting fixed.

Basically: If it it works on your car, great. If it doesn't, it probably never will.

I know how it's supposed to work, my family has owned other cars with the same keyfob/system, and it works perfectly.

shrug