Good idea to re-read the instructions. Anyways, yes, it only works on the 3DS you are using, because each system is encrypted using a key that is unique to that hardware, so you can't use the emunand from another person's 3DS, since their key will be different from yours. So don't bother trying to get someone else's emunand, because it won't work. I assume you're asking because you updated your system and now you can't use Gateway?