Check the ingredients. A quick search on hemp milk found me this:
Tempt brand hempmilk:
Hemp Nut Base (Filtered Water, Hemp Nut [Shelled Hemp Seed]), Brown Rice Syrup, Organic Evaporated Cane Juice, Tricalcium Phosphate, Carrageenan, Sea Salt, Vitamin A Palmitate, Vitamin D2, Riboflavin, Vitamin B12.
All seeds and nuts are paleo.
Got milk? "Hemp milk is one of the most nutritionally value-packed milk options. Hemp milk is a great option for vegans, those who have allergens associated with whey protein or casein, or are lactose intolerant. Hemp milk is full of omega fatty acids, minerals, vitamins and protein - not to mention easy to make!"
Hemp Milk 1 cup hemp seeds 5 to 6 cups of water Sweetener: honey or agave
Directions: In a blender combine one cup of hemp seeds with five to six cups of water. Blend for two to three minutes until smooth. Use less water for a thicker option. Add sweetener to taste. Strain through a cheesecloth or strainer to remove seed particles. Keeps fresh for three days in the refrigerator. Great for coffee, cereal, or oatmeal.
Ok I know you are wanting to do the strict paleo diet but look at the nutritional value of hemp milk and ask your self if the faddish paleo diet is worth cutting out healthy foods because they aren't on the list. Use your brain and listen to your body.