The idea behined this kind of button is that when you have premium account/event, you essentially does not need to use +30% exp item, when you lvl up low lvl crew.When new chinese nation will be introduced in may, everybody will be lvling up them, and i think it would be just in time to implement this feature.

I imagine after login i go to item bar, and after i type 2nd pass, i can disable/enable +30% item.In battle room there should be info if button is disabled or enabled for player to be sure what status of item is.

This is very simple, easy to implement, and imho really worth consideartion idea.Please share idea with friends and reccomend!