Sir, can you explain what is that Lucky Box?
Sure
Every month, iRO's Kafra Shop releases an item called Groove Pack/Lucky Box that contains random goodies and items.
They rotate each month, for example, January was Groove Pack, February was Lucky Box, and now we had another Groove Pack this March and we'll have a Lucky Box in April.
Groove Packs cost 150 KP, they have a 100% guaranteed item (normally consumables like Certificates -for upgrading-, Manuals or Branches or HE Gum) and a random item from a list.
Lucky Boxes cost 300 KP, all their items have a random chance but are usually very valuable items (Like the Prize Medals everyone is talking about, or FAW -Fallen Angel Wing, but only in very special ocassions)
Now, in Eden Group's 2nd floor, there's and NPC called Grandma Boxter. If you get an item from a Pack/Box that you don't need/want you can trade it to her for 'Brownie Points' (each item has a different conversion rate into points), once you get 1000 Brownie Points you can trade them back to her for another unopened Pack/Box (This was what ChenChen12 was refering to)
Boxter's item list as well as the Box/Pack she gives out are also rotated in a somewhat monthly basis.