For example, say you want to track Pro usage and billing separately for different business units. To do this, create multiple Pro subscriptions linked to separate Google Cloud projects, with each project using a different billing account.
On the other hand, if you want to track Pro usage separately for different business units but pay for their usage from a centralized cost center, you can create multiple Pro subscriptions linked to different Google Cloud projects, with each project using the same billing account.
If a user is in multiple Google Groups in a subscription, you will be charged for a license only once for that user. However, if an individual user belongs to multiple subscriptions, you will be charged for a license for each subscription that user is in.