is this game still in development or is it completed? cause i paid for it and i am afraid that if it is still in development i will have to pay more in the future to keep playing
As it says right at the top of the page, the game is complete.
Also you don't need to pay again for each update. If you've got an itch.io account the game will be in your library and you can redownload at any time. You should also have an email receipt of your purchase with a redownload link... so yeah, don't pay again for stuff you already own, be it our projects or anyone else's.