"as long as" means "for the length of time" that something continues. For example "You can stay here as long as you like". "He lived there as long as he could pay the rent".

In addition to Ruthi's answer, it can be used to indicate that any condition is true. I will go as long as you agree to go, too, As long as you play with him, he will like you. There is no sense of time here, but only whether something is true or not.