Looks like so many ppl are interested but no answer...

Come on! Somebody tell us~~

Not really sure bro, I dont know if they change the current system for it. You should ask those on the TNF instead or send a ticket but then again you can ask some of the players if you get on the game. 

If your friend decides to play NavyField after the free premium subscription, there will be additional gifts for both accounts when your friend purchases 3 months of Premium Subscriptions.

- Gift for you : You will be able to choose an EBB that you want, or select a pack of premium item set we have prepared.
                          You can choose one type from
                            A. 1 month Premium subscription
                            B. Experts+100(x2)(4EA) + Veterans+10(x2)(1EA)
                            C. 1 H.Q. Expansion

- Gift for your friend : Your friend will be able to choose one of the premium ships that are currently sold in the N.F
                                       Store. (PCA, PCL, PCV, PBB from any nation.)

- Notice
  1. Your friend has to purchase 3 months of Premium Subscription to be eligible for the gifts.
  2. Gifts can be redeemed after 1 month from the accept of invitation.