Battlefield 4 pre-order and premium pre -order

So, I bought bf4 preorder in a box, typed in the code, it says I preordered bf4 but to play I will still have to buy the game but I will get a discount(the price of preorder box with the code). Everything is nice and it says I will get premium expansion pack. Does it mean that I will get premium for free or its just one DLC and to have premium I will have to buy it? Because I would like to preorder premium. http://puu.sh/48UUs.png