GCP BigQuery expression tracking monthly invoice of all resources in a specified project based on assigned labels values

gcp-bq-invoice-labels.sql

SELECT
  labels.key as key, labels.value as value, invoice.month,
  (SUM(CAST(cost AS NUMERIC))
      + SUM(IFNULL((SELECT SUM(CAST(c.amount AS NUMERIC))
                    FROM UNNEST(credits) AS c), 0)))
      AS total
FROM `<FIXME_project>.<FIXME_dataset>.gcp_billing_export_resource_v1_<FIXME_BILLING_ACCOUNT_ID>`
CROSS JOIN UNNEST(labels) as labels
  ON labels.key = "<FIXME_KEY>" and labels.value = "<FIXME_VALUE>"
WHERE project.name = "<FIXME_PROJECT>"
GROUP BY key, value, invoice.month
ORDER BY invoice.month;