If your subscription has not expired yet, enable auto-renewal to enable automatical renewal for the next billing period. You can find instructions in KB 123306.
If your subscription expired, follow the steps below:
Go to the Subscriptions and Licenses > Personal Subscriptions page in My Account:
Click on the subscription you need to renew.
Click on Renew online.
- Proceed with the purchase.
If Parallels Desktop stopped working due to the expired license, you need to restart Parallels Desktop after the license is renewed.