 <p>If you're load-balancing, you're going to want the additional license to be the for the same platform as your existing license, because the point of load-balancers is to divide the work between multiple identical systems.</p> <p>If you don't already have dependence on other Magento Enterprise Edition features, I would recommend against getting an Enterprise license if you are considering load-balancing. Because of the way Magento is licensed, you would require an additional Enterprise Edition license for each installation of Magento, and that includes each instance behind a load-balancer.</p> <p>If you are considering expanding your infrastructure to include multiple instances of Magento, it is probably best to contact a Magento sales rep, as they will have more-specific information about licensing restrictions, and may be able to negotiate a package which suits your specific needs.</p>