Do NOT buy this via the App Store! The version you can directly download from the jinx web site is at version 3.18 and even seems to work under Mountain Lion! The cost directly from the jinx web site (via esellerate) is a bit higher than through the App Store but, again, the App Store version doesn't work.
I already had a license via the App Store and followed the directions on the jinx site but the new version said it was unregistered so I ended up buying a second license to get it activated.
So the answer is to pay the extra cost to buy it direct and don't spend the money at the App Store.