Use the verb appertain when you need a formal way to say "officially concern." For example, you could argue, "Those mall rules don't appertain to me and my skateboard."
You're most likely to see the word appertain followed by "to," meaning "apply to" or "relate to." Your parents' instructions, for example, appertain to you and your sisters; and passport laws appertain to any citizen who wants to travel to foreign countries. A closely related word is pertain, which has a similar but less formal or official meaning. Both words come from the Latin pertinere, "to relate, have reference to, or be applicable."