Checked on it using the app to see if .........
The app is handy for checking the doors are locked, finding your car, flashing the headlights if you're close but can't quite find it, amongst a ton of other stuff that it shows. 
Apparently it will flash the lights and open/close the windows from 100+ miles away.
The dealer selling the car is going to be upside down once they've either figured out that the previous owner still has app control or given up on the mysterious electrical gremlins 

Yes, you're correct, it would. The request to check doors, windows, fuel level and flash lights etc. goes to BMW Control Centre first, and then goes to the vehicle. When the vehicle is new, the first owner gets 3 years subscription to use the app/consierge etc after registering the vehicle VIN. When the vehicle is returned/part exchanged, the dealer should perform a software wipe out. This erases any consierge requests sent from the vehicle, any navigation inputs and removes any music from the hard drive, but I'm not entirely sure if it blocks the app unless you terminate it yourself.
