Google Cloud billing works by charging a monthly fee for the amount of data used by a user. This data can be in the form of uploaded files, processed data, or active usage.
In order to account for usage, Google uses a usage meter that records the amount of data used by each user. This meter can be found in the Google Cloud Console under the Billing and Cost settings for a project.
When billing begins, the usage meter is initialized with the total amount of data used by all users in the project, as determined by Google. This total amount is then divided by the number of days in the billing cycle.
This number is then multiplied by the monthly fee to get the amount that will be billed to each user.