If you have the enthusiast version, you can have 10 VIN Numbers stored on the unit, and thus can connect to up to 10 bikes. When you connect the unit to a bike, you will be prompted whether you wish to add the connected bike. If you confirm and have some of the 10 slots open, the unit will add the bike. You cannot later delete any VIN number stored.
The Professional version has no limit on number of bikes.
That's my experience/understanding.