You need to assert your dominance as the "leader of the pack".
Your pup should never nip you after you tell him the game is over.
It's easier when the "puppy" doesn't weigh 80 lbs
but if you are physically able, try picking the dog up off the ground. Keep all four feet up and hold him until he settles down.
Make sure he knows it is not a game.
If he still won't submit, wrap a hand around his throat.
Don't use much pressure at all, no need to hurt him.
This seems to impress upon Poochy just who is the boss.
It's worked on my dogs in the past.
HTH
Your pup should never nip you after you tell him the game is over.
It's easier when the "puppy" doesn't weigh 80 lbs
Make sure he knows it is not a game.
If he still won't submit, wrap a hand around his throat.
Don't use much pressure at all, no need to hurt him.
This seems to impress upon Poochy just who is the boss.
It's worked on my dogs in the past.
HTH