I used Washi tape, which sticks really well, but will come off later. And let's face it, it is pretty. Then I used my label maker, which is always loaded with clear labels, to put the codes on the systems. I am completely addicted to clear labels. If there is a 12-step program for that, I would get the promotional flyer and mark it with a clear label. My husband has been known to hide my label maker. He said he thought he might come home and find labels on the dogs. I then pointed out that they have collars on with their names on them.
It is hard to see in the picture but the Showroom system has a blue and white chevron patterned tape. The Pink tape I used on mine is much easier to see. I am not sure why I needed to put #1 on both of them. Could be that I am fantasizing about getting more systems. Can't you just see a showroom full of them. All happily quilting away...
If you are bringing your tablet to a class you really want to mark EVERYTHING. Your tablet, your plug, the stylus, the charging brick, the USB. There may be as many as 13 identical systems at Quilt Path Camp. You want to make sure that you go home with the one that has your designs on it.
I have an assortment of Washi tape that I will share if you come to class without your system marked. Unless it is your stylus, because mine is missing in action. I swear that thing has legs!