New Post: Downloadable products are always downloadable.

I'm trying to configure the NBStore module for downloadable products, but I'm running into one difficulty. If a user looks at the product page, the text "Download your purchased files here after payment" is displayed appropriately, but immediately above that text, the download links are visible and active even if the product hasn't yet been purchased. In other words, just by looking at the product page/description, a user can download the product whether they've purchased it or not.

Obviously I've missed a configuration step somewhere, but I can't for the life of me figure out what it is. Any thoughts on what would be causing this behavior?