Most items in the Boost category on the Aion Store, the Black Cloud Marketplace, may be used only once, by one character on your account. The exceptions are items labeled Boost Packs.
Because Boost Packs are not specific to a particular character, you won’t see your character’s benefit displayed the same way other benefits and buffs show up. There is no icon displayed when a Boost Pack is active.
Instead, you can confirm that a boost is active and see how much time is remaining by clicking the green up arrow to the right of your skill bar, choosing Support then choosing Account Info. In the Account Info window that appears, there will be a Current Active Boosts section, where any boosts that are in effect will be listed, along with the amount of time remaining for each.
Berdin's Amulets are not Boost Packs, but they are different from most other experience boost amulets in that they can be stored in your account warehouse. You’re welcome to transfer them between characters on the same server using that feature. However, unlike other amulets that can be purchased on the Black Cloud Marketplace, Berdin’s Amulets cannot be traded between characters directly.