there is a game that has a version for 5$ and i bought it, and for an update i need to re install that version to play it but the game is currently under maintenance and since it disapeared from my Library i was wondering if i needed to buy it again or not (IK ITS STUPID BUT IM WORRIED ID HAVE TO)

From my understanding, as long as they put their new version as an upload of the same project page and with the same price tag, you should still be able to access all available (new) files to download them. If they would put the new version onto a new project page entirely, or set a higher price than it was before, you would not. (Edit: Assuming they used the price-tier-system to give out the paid-version.)