Buy 3 marrow bones. 1 to hide for dog to 'find' in garden, 1 for inside. ALWAYS have marrow bones, and your dogs need to chew/rip/tear/grind can be employed gainfully, and the teeth will last a lot longer.
At 7 months. Id be coming down hard on him as he's in adolescant area nearly where pups go temporarily deaf and forget training. Id hit training hard for next 3 months to help him through his puberty.