Hey Konoi! The $9.99 is for Chapter One only because it contains 10+ hours of gameplay (not including replay-ability) and basically a full game within itself. The final release of Faulty Apprentice will be priced at $19.99+ and I believe you'll be able to put the $9.99 towards the final game release (like credit) but I'm not 100% sure how that works here on itch.io, so please only purchase if you would like to donate towards Faulty Apprentice development.
Thank you for being interested in Faulty Apprentice! -din