There was an iOS app I used like this that did a great job of scanning text books.

After I used it for about 6 months this exact thing happened. Started charging fees for many different things.

Exporting images as pdf had a charge, then scanning to make the text searchable had a fee.

I just exported as jpg and used imagic and ocrmypdf to take care of this.

Then I learned that iOS has a built in scanner in the files app, so I just switched to that one.