Applies every quantity change in changes to the subscription as one update and bills it right away: the whole change set produces a single prorated invoice. Only lines whose quantity actually differs are applied and reported, and a change set where nothing changes is rejected with 400. There is no undo — price the same change set with /api/v1/licensing/preview/batch first. The subscription must be one of your account's, and a single billing action-log entry summarizes every line.