HI,
OCR engine is 2 types : Local and Cloud.
Local based OCR engine such as MicrosoftOCR, Tesseract or OminPage is free in UiPath environment.
On the other hands, Cloud OCR such as Azure Computer Vision, Google Computer Vision or UiPath Document OCR for digitize purpose basically requires fee except under certain conditions.
For example, in Azure Computer Vision there is free plan and we can use it within 5000 transaction per month.
Microsoft Azure Computer Vision
Google Cloud Vision: we can use it with no charge in first 1000 units per month.
Or we can use UiPath DocumentOCR for free in Community Plan.
Hope this helps you.
Regards,