SAMP 2.0 does not allows to have symbols like !@#$%^&*()=_ that's why you cant have name with one of these symbols. Now the second thin, you can install 1.0 or 2.0, however Argonath is working only on 2.0. That's why you cant change, this what you have in old one. About license. License you have to get again from admin, that's the only way.