adverb clause...

Hi,
I know that if an adverb clause starts a sentence we need comma after them and if not, we do not use it.
But I saw some sentences in dictionaries that use comma although adverb clause is not the first sentence.
Like these ones from Cambridge dictionary:

She walked home by herself, although she knew that it was dangerous.
He decided to go, although I begged him not to.

Can we use comma like that?why?