Yes it is legal, but why spend so much on something like this when you can buy 1kg of creatine for <$20 (200+ 5g servings), 10lbs of quality whey protein for $50 (over 160 servings), 100 grams of caffeine for <$5 (500x200mg servings) and get much better effects for a fraction of the cost.
Don’t bother with these fringe products if you aren’t using a decent multi-vitamin, protein, zma (of some sort), and fish oil.