I can't imagine that it would get you into any legal trouble, unless you live in a strangely authoritarian country. BracesShop has a company policy against self-treatment, but that's obviously different from a law, and as long as you don't advertise, "I am ordering this explicitly for self-treatment" then you should have no trouble. I'm waiting for my appliance to ship and haven't had any difficulties. Neither have I heard from anybody else running into any trouble.

Please, just be cautious about how you use the device that you order, and if you can afford it, at least have a meeting with a functional orthodontist / myofascial practitioner (that's what I did). Good luck!

@elwynn

Thanks for the help! I live in Hungary and I hadn't found one one functional orthodontist... And I mainly want to use the device to track my progress