There are several possibilities that may cause a dog to stop biting:
Age: Dogs will undergo different physical and psychological changes as they grow. As your dog matures, he may reduce or stop biting.
Training: If you took the time to train your dog, he may have learned the behavior of not biting. If you regularly provide your dog with enough toys, bones, or other suitable chewable objects so that he understands what he can and cannot chew, he will understand what is allowed.
Health: The dog may stop biting because of physical discomfort. Issues such as tooth pain, gingivitis, and digestive issues may cause your dog to not want to eat or bite.
If your dog has stopped biting but you are concerned that he may have a medical problem, contact your veterinarian for a check-up. If your dog has stopped biting due to age or training, then this is a good change.