Bite inhibition is a crucial skill that a puppy must develop if he is to live peacefully with his human and dog family. Bite inhibition is the dog’s ability to moderate the force of his bite. While dogs often use their mouths in play, they must learn when they are using too much force. This needs to become a reflex and is best ingrained in puppyhood. 
The dam of the litter aka your puppy’s Mom, along with his littermates are without a doubt the best creatures to begin teaching your puppy how to control his mouth. This is a reason why you shouldn’t take a puppy away from his mother and litter before 8 weeks of age.
During his time with his mom and siblings, when an excited pup bites Mom too hard during a play session, Mom will give a yelp loud enough to startle him. If he bites hard again, Mom might growl and show teeth. She also might bite back. She certainly won’t continue playing with a pup who bites too hard.