Nut butter is fine for a protein serving, as long as it wasn’t a binge food for you. However, it may slow down your weight loss, so eat it 1-2 times per week at most during the weight loss phase. You can also split your protein serving and have half nut butter with half soy milk or almond milk, for example.
2 oz. = 1 protein serving for women
2 oz. = 1 protein serving for men