If you buy the game from the 3DS eShop remember to back up your game on your computer. Nintendo does things differently then Sony, and Microsoft with digital purchases, and they don't tie digital purchases to your account. So if you do a hard reset on your 3DS, or your 3DS breaks and you buy a new one, if you didn't back up your digital purchases you will pretty much be out of luck, and be forced to re-buy them.