Unfortunately this is just the free demo page, and the option to pay is purely donation. When the game is completed, a new page will be put up on itch.io for the full version of the game for sale.
At the moment, Patreon is the only way to gain access to the latest builds of the game.
That being said, the game is quite close to completion. The estimation is that it will be completed, and up here on Itch.io, and on Steam in December. The target price on these platforms will be $14.99 USD.
Thanks a ton for the support ^^. I'm glad you enjoyed it!