Well im suppose to get this key for this mod called splinter manor, but i kinda turned into a werewolf at the beginning and went to vos to buy the key and he turned into combat and he don't have the key on his body.
Isn't it obvious??
Of course the NPC is going to attack you if you're a werewolf. Werewolfs can't start dialog with people anyways.
Since he doesn't have the key on him, it's probably because he just gives it to you through dialog.
You can open the mod in the CS and find the key's ID, then add it to your inventory with the console.
EDIT: confirmed. He gives it to you through dialog.
If you can't resort to an earlier Save, the key's ID is