When the application plan is changed in the middle of the month, the variable costs that are calculated on the 1st day of the next month are calculated according to the pricing rules of the new plan.

This is problematic, as the following situations may happen:

1) Application is on plan A with $0.01 per hit, from the 1st till the 30th day of month it makes 1000 hits, and on the 31st day the app switches to plan B with $1.00 per hit. On the 1st day of the next month the app is billed 1000 hits at $1.00 price. So, $1000, even though it should have been charged $10 ($0.01 x 1000).

2) And the opposite. The app is on an plan with pricing rules the for whole month, e.g. $1.00 per hit. It makes 1000 hits, and then switches to another plan with higher fixed monthly price, but no or very small price for metrics usage. So, on the next month it doesn't get billed for the variable cost.

Proposal is

• Make "Instant Bill Plan Change" the default behavior for new accounts and for accounts that enable billing after this change.
• Keep the configuration being used for existing accounts that have billing activated.

Dev Notes