When you upgrade, the balance of time remaining on your existing plan is fully accounted for and you'll be compensated for this balance.
In order for this to work, you must upgrade using the same platform/device (iOS, Android, or Web) that you originally used to purchase your plan.
See the specifics for your platform/device below:
Web
For iOS devices:
Any remaining balance for your existing plan will be refunded back to your Apple Account's payment method. Your new, upgraded plan will begin immediately at the full plan price.
For Android devices:
The remaining balance on your existing plan will be used first, and you won’t be charged for your new plan immediately. After the remaining balance is used up, your new plan will begin.
For example, if you upgrade from Pro Annual to Elite Annual half-way through your plan period, the remaining balance Pro will be converted to time on your Elite plan. Once that balance runs out, a new annual plan will begin for Elite.
On the Web (laptop/desktop computer):
The remaining balance for your existing plan will be applied as a discount to the cost of your new plan.
Please note, you'll always see the full price for your new plan listed in the app when going through the upgrade process. You'll see the discount listed on the receipt sent to you by email immediately after you upgrade.