If you have an active Parallels Desktop subscription, you can use a new license key to extend it.
Important: applies to subscriptions that are not purchased online, such as gift cards, keys received upon completing the Parallels Desktop Training for Authorized Resellers (NFR keys), boxed copies.
Extend in Parallels Desktop
1. Click on Parallels icon on Mac menu bar || > Account & License > Enter a key.
2. Enter a valid NFR key and click Activate.
3. Choose to 'Extend an existing subscription' on the appeared pop-up > select active subscription and click Continue.
Note: the operation is irreversible.
Now your subscription expiration period is extended.
Extend in Parallels My Account
Go to Parallels My Account > log in to your account > click on 'Register Key' on navigation bar > enter subscription key > if you have an active subscription you will get the following message:
Click Extend or Register to extend existing subscription or create a new one correspondingly.