Transcription usage is based on the length of the video being transcribed.
Usage is only deducted at the time of the initial transcription. Any further actions—such as creating short-form content using segments of the transcript, moving parts of the transcription into a new sequence, or clicking "Apply to Sequence"—do not incur additional transcription usage.
Note:
When using the "Full Clip" option for transcription, be careful. If the original clip contains unused footage at the end within the Premiere Pro sequence, it may lead to unintended overuse of transcription usage.