How to create a promotion that upgrades tier by one month?

Hello,

Сould you advise the better way to create a promotion?

The main idea of the promotion is that a member's tier will be increased by one month if within a calendar month a member buy a certain amount of partner products.

For example, we have:

• 5000 points limit for product A
• 1000 points limit for product B

A SILVER member has transactions with such attributes:

• accrual, product A,1000 points, 10/04/2020
• accrual, product A: 4500 points, 12/04/2020

So, the member must get a GOLD tier from 12/04/2020 to 12/05/2020.

If the member gets a 1000 points transaction of product B on 18/04/2020 after tier upgrade, then end GOLD tier date should be shifted to 18/05/2020.