To put it bluntly. The program was already available in the "App of the Day" promotion for free, basically, it is a commercial version for just over 10 euros. For Android conditions a steep price but I am quite prepared to pay well for good programs and have already actually bought some programs at this price range.
But with such a price I do not expect additional costs for basic functions. And outsource core fonts in an Office package encounters strange.
To the developers:
Take the scriptures with the program and adjust price. Or in the description of the program fair to point out optional fee-based additives. Then there's no nasty surprises