Konattchi

Truth be told I think that the real use of premium is for the cash reward. The cash increase is not something to be taken lightly and its valuable enough to be wanted even if you have maxed out your characters.

Since reaching lvl 255 is very grindy and not very motivating to make a second character I suggest to add a perma exp bonus after a max out. This will stimulate players to buy characters slots and it would be even better if this stacks. Maxing out 1 character x2 exp for next one. Maxing out 2 characters x3 exp and so on.