It’s a good question. I’ve paid for this app but find it virtually useless because it doesn’t integrate with the iOS file browser functionality. This issue has been outstanding for over a year now.
If it was open source I’d be happy to see if I could contribute to rectifying the problem but it’s not as you pointed out.
I’m surprised you mention there has been a price hike when it still doesn’t have this functionality. I’m all for supporting open source and software entrepreneurship but it has to work.