That does not make sense, since when you buy it, you wont have to buy again from them. Your downloads are at the My Library, but you can also just click on the butten at the top of the games site, and should still be able to download it if you have already bought it. So either you have not bought it, or you trying to get a freebie.
If you go to the top of this site and it says "You own this game" then you have access to it from the one that says download, and not from the "Buy Now" or the demo.
There are two buttens that say download, and one of them are at the top of the site.
Also dont go to the development logs for the downloads.