The extensive research & development that went into the product. When you subscribe you also get a lot of scientific insights. If you're a biohacker, this is a product you want to add to your list of ones to use/test. Although you will NOT notice anything (I haven't so far and I've been using this product for about 2 yrs of use), if you believe in the science, you hope to after long-term use.
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Cost of subscription; needs to move towards sustainable eco-friendly packaging.
