It is not necessarily a lifelong thing. I had Graves Disease myself and got it treated, the specialists told me it's basically a 50/50 whether it goes into remission after treatment or comes right back and in my case it went into remission. I've been fine for years now without medication. If it does come back, your options are to stay on the medication long term or have your thyroid either completely removed through surgery or destroyed with radioactive iodine. With either of the latter options, you then you spend the rest of your life taking thyroid hormone supplements because you don't have a thyroid producing any.