Hi! I bought the premium version through here ($9.99), and was wondering if this purchase includes all premium content for future updates, or do I have to pay $20 for that? If not, I didn't get a premium key and I'm not really familiar with itch.io so how would future purchases work?

Hi, 

Your one time payment was it. Whenever we update the game, you'll download the new version we uploaded. As long as you are logged into your Itch account, you'll be able to download it for free. We recommend the Itch PC client because it's a nicer way to keep the game updated and should auto update itself if we've released something new. 

Ok thank you!!