These three expressions are similar. So, they may cause some misunderstandings. Although the three expressions have the same meaning, you should be careful how you use them. They must be used in different kinds of statements or questions.
“Any longer” is an adverb, that is, it gives us more information about the action in a statement or question. It means that something that was once true or possible is not now true or possible.
• Because of the coronavirus, we can’t sit close together at the movies any longer.
• Don’t you go to that store any longer?
Note that the sentence has a negative (can’t). You will only find this expression in questions or statements with a negative.
“Anymore” is an adverb when written as one word, meaning that something that was once true is not true.
• Chris and Sandy are not dating anymore.
The expression “no longer” appears in statements or questions without other negative words. The word “no” is a negative already.
• I will no longer eat pizza before going to bed – it gives me bad dreams!
Note that “no longer” can appear in the middle of a sentence.