What is Proration?
Proration applies only to monthly-renewed subscriptions. To avoid getting you billed of unused time, on first month you will be billed only for the remaining part of the month. This is proration, and applies only to the not-first active purchased app of a plan.
It can be understood better with an example.
If you wish to remove commissions from your app A, you purchase a monthly subscription. Purchase time gets registered, and will be marked for renewals. If 15 days later want to remove commissions from app B, on first month you will be billed only 50% of the price, to sync both cycles to the same date.
This only applies to same products. For example, if you were to buy branding removal for app B without having branding removal on app A, cycle will start on that day. Proration would apply to app C when removing branding.
Be aware with coupon codes. Coupon codes apply to the first month of the purchase only over. If proration is applied, coupon will be applied to the prorated amount, not the whole amount.
Thus, it is recommended to apply coupons only to yearly subscriptions or at the start of cycles.