You can pair one key fob to as many Monimoto units as you like. For example, your car and your motorcycle - you can use same key fob since you would not drive both vehicles simultaneously.
When pairing Monimoto with a new key fob that is already paired with another device - it's important to make sure that you only have that one Monimoto unit within 10m range at that moment. Otherwise, you can not add the same key fob to the other Monimoto device.
Note that you may need to connect to your Monimoto in the app via Bluetooth just before you ride your motorcycle.