You can use the GS911 to find faults and clear codes on as many motorcycles as you like, the 10 bike limit (Enthusiast) is for resetting the Service Indicators to the bike.
Having now received what I would term Diabolical service from people who don't give a fcuk about your bike (yes a BMW Motorrad dealer) I have taken to doing most of the servicing myself. Having a bike still in warranty is a downer for sure.