Proper storage of a guitar controller:
The first thing to remember about storing your guitar controller is not to let anything rest on its face. Don't store it face down or set anything on top of the guitar controller. While your guitar controller should be fine laying flat on its back for long periods of time, horizontal surfaces tend to get things set on top of them. And, for that matter, it seems like every time something spills or falls, it does so in a downward motion. For this reason, I would suggest storing your guitar controller in a vertical position, perhaps in a corner of a room. If you have a drum set, as well, you could do what I often do; store the drum set in a corner and let the guitars lean against the edges of the drum heads. The ridges in between the drum heads do a good job of keeping the guitars from falling over. If you are
really worried about the guitar controllers, however, there are things you can purchase to protect them. In fact, what people often do to store real guitars would work here as well. There are guitar stands that are sort of tripods with rubber-wrapped parts to cradle your guitar (or controller), gently, in a upright orientation. Some include a rubber or plastic piece that locks the neck in place so the guitar doesn't fall out if it gets jostled. I have used a guitar stand without the locking piece with my bass guitar, 2 acoustic guitars and guitar controllers, and this has never been an issue, but if you want the extra precaution, it's available.
Another option, and one that Cyn uses in her home, is to hang the guitar controllers from the wall. There are special hangers that are rubber coated and are designed to allow your guitars to be stored up on your wall, where they can both be up off the floor and safe from harm, as well as providing something to help decorate your room.
Still another option is to use something called a "gig bag." This is a padded bag designed to protect your guitar (or guitar controller) when you carry it around from place to place. There are gig bags made specifically for guitar controllers, in fact. These are smaller than gig bags made for real guitars, since the scale is different.
Finally, if your guitar has a cord, be careful not to wrap the cord too tightly when storing it. Wrapping the cord in a tight circle or wrapping it tightly around something else (such as the guitar controller) can put undue stress on the wires inside of the cord, causing them to eventually break. You should wrap the cords in larger loops, loosely, and then tie a cord management wrap, such as a Velcro wire tie around it. Never tie the cord around itself and into a knot. This makes really tight bends in the wire which is bad for it, as mentioned above.
A Final Word:
If you have any problems due to manufacturer defects, they typically show up quickly under normal usage and often will be within their warranty period. If you don't have such defects, and you take good care of your guitar controller, it should last for a long time.