Also to add to what @Pummy_Raj has posted (very well too) King can only replace purchased boosters as the free ones that are earned or won, are only kept in the device memory and not saved to Kings servers. This way you can access them while offline too. They also recommend for the reason of them occasionally getting lost, that you don't save too many as more often than not its a device error that causes them to vanish when its updated It can happen by update although it is rarer.