If your current GB subscription is insufficient, you can upgrade it. When you upgrade a GB subscription, you must pay the difference in price between the original and upgraded GB subscriptions.
Billing
When you upgrade a GB subscription, you pay only the difference in price between the upgraded GB subscription and the original GB subscription. The following method is used to calculate the price difference for an upgrade:
Upgrade price = remainder of subscription lifecycle × (newly subscribed GBs - originally subscribed GBs) × unit price of GB subscription
For example, assume that at 15:00:00 on August 15, 2019, you purchased 10 GB for one month. In this case, the resources expire at 00:00:00 on 2019-09-16. The duration is 31 days and 9 hours. Assume that you upgrade the GB subscription to 15 GB after you use it for n hours. In this case, you also pay for an additional 5 GB resources for the remainder of the subscription lifecycle. The equation used to calculate the cost is (31 × 24 + 9 - n) × 3600 × (15 - 10) × 0.00003167.