A Looker Studio Pro subscription can link to a single Google Cloud project. To link Looker Studio Pro to multiple projects within your organization, create a new subscription and link to each project separately.
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.