Melt 6 tablespoons butter in a skillet over high heat. Add shrimp; cook and stir until browned, about 2 minutes. Reduce heat to medium-low. Season shrimp with 1 1/2 teaspoon lemon juice, garlic salt, salt, and pepper; cook for 1 minute. Serve with remaining 2 tablespoons butter and 1 1/2 teaspoon lemon juice.