this is a one-time payment; you will not incur any further expenses.So, full disclosure, I went and subbed to them and downloaded it and was going to share here...but I'm not even exaggerating, the TWENTY FUCKING DOLLAR demo version has maybe 4-5 more scenes than the free version prior to them splitting into a paid and free version. This game is great and has excellent content, but holy shit do NOT shell out for the paid version; they quite literally just put a 20 dollar price tag on a chapter (the Desert after you complete the demon world) that was already in the game prior. It's a classic case of paywalling existing content.
Edit: Just in case it wasn't clear, not bashing the dev for charging for what is genuinely a massive amount of content in terms of the free and paid demo combined, but for intentionally stripping out content that was already in and charging an absurd amount for it. I'd find it more fair if they just got rid of the free demo and just charged 20 bucks for the whole shebang; at least then you're not getting baited into paying for next to nothing.
In fact, I value any promises very much, so i think this fee should be discounted by at least 50%.