Keys not on keychain?

Hello, I got my V70 yesterday and read the manual yesterday evening (sometimes only flew over (-; ). To the key it says that you should not make the car key to a keychain with other metal keys. This would have adverse effect on the roadway lock and could cause you to start no more. How do you handle this? I actually only have two keys together with the AUto key. Does this or do I actually have to handle the Volvo key separately. How is it with aluminium (is also a metal)? On business trips with the plane I usually pour the key into my Rimowa suitcase. Best regards Matthias