If you exceed a free tier text recognition (OCR Tool) service limits you will be offered to order a premium plan from this page: https://convertio.co/ocr/pricing/ .
You may choose any prepaid package that suit your needs.
These packages are not expired, you may order a big package and use it for years.
These packages are not automatically renewed.
These packages are one-time payment.
These packages are additive. You may order another package before previous run's out.