I would like to have a load balanced setup, does my current license key cover all of these servers?


No, because load balanced servers allow more concurrent users to be connected at the same time, each load balanced server is licensed individually. For example, if you want each load balanced server in your pool to handle 25 concurrent connections, and you have 4 of these servers in the pool, then you would need 4 x 25 = 100 concurrent licenses total.