We have got  3 forms of subscription now:

  "3 DAYS PREMIUM ACCOUNT" -  40 olives
  "7 DAYS PREMIUM ACCOUNT" -  80 olives
"30 DAYS PREMIUM ACCOUNT" - 200 olives
 

with bonuses
* 40 % experiences/credits/points
* double experts sailor gaining chance during the battle
* veteran conversion success ratio plus 50 %
* bonus 1000 extra experiences by being in battle for 5 minutes
* 12 additional slots of h.q

and sailor item:

"EXP +30 % BONUS" - 80 olives

with bonus
* increases experience for 50 won battles.

I want to propose change (and maybe move it to form of subscription) this item on:

"+70 % BONUS EXP CONTAINS A SET 120 USES FOR WON BATTLE" - 200 olives

* increases 70 % getting of experiences/credits/points by being 5 min in every from 120 won battles
* the cost of this subscription for 200 olives
* this item couldn't may be combined with other form of subscription (except getting bonuses from event days) 
 

Additional explanation

Why is 70 % there?
Because the premium subscription with +40 % exp with sailor item exp +30 % gives also 70 % experiences.

Why is cost only 200 olives if a premium subscription with exp +30 exp bonus item costs 280 olives?
Because item "+70 % exp bonus" could give only bonus to experience/credits/points without other bonuses like the premium subscription and it couldn't be combined with it.

Why are 120 battles there?
Because 4 won battles per day in month gives 120 battles (it's standard from playing minimum 1 hour or more time - you know it from event days), so this number of battles is comparable in time of 30 days the premium subscription.
 

Where did the idea?
I guess this form of subscription may be more convenient, more flexible for players but also it will increase their amount on the server and revenue for the developer, so generally better for all of us.