It is stated in their terms and conditions:
"4.4 We only sell our retail products to final customers. Your order on our Website or by telephone must have no direct relationship with a business activity and must be strictly limited to your personal use.To ensure better service and better availability of our products, Louis Vuitton limits the quantity of products that can be purchased as follows: no more than 3 leather goods (including small leather goods) products per transaction, with no more than 2 identical products per such transaction. Also customers cannot, within 4 consecutive weeks, (i) buy more than 6 leather goods (including small leather goods) products, or (ii) buy in more than 3 different Louis Vuitton stores (physical or online) in the worldwide network, or (iii) conduct more than 8 transactions of all kind of products. In any case, the total number of purchased leather goods (including small leather goods) will not exceed 12 products within 12 consecutive months. In case of non-observance, our sales associates may refuse further transactions with you, for a period of 2 years from your last purchase."