I read through the post again, and I honestly have no idea how OP managed to wear the sticker off, unless it was through poor usage. There is a ski-goggle style band that wraps around the metal headband (which the S/N sticker is on), but does not touch the sticker in any way (first picture, different model but similar design). It doesn't matter how you wear the headphones, it just won't make contact. I've gone through 4 pairs over the years (even bought a second hand at one point), and the longest one I've used was about a year. The stickers were clean and visible in every pair. OP said they recently bought the headphones (assuming a few months ago from the box comment) and the sticker already wore off. As I already mentioned, the stickers never wore off even after a year of use, and the stickers do not make any contact with anything even when you wear them.