Is the game finally finished? Is that why it has a price tag? Or is it not and you can get an update later after purchasing?
It has a price tag because it is also on Steam, and Steam has issues with content on their platform being hosted elsewhere at a different price. The game is only a 1 time purchase, and all updates will be free. If you were worried about having to pay for each update, don't be, as that won't happen. For more info, read the "Update News and future pricing" dev log above.