If you want to upgrade your subscription, such as switching to Pro Yearly in order to download HD videos, submit work to pro Live Events, or take advantage of the perks program, then you can do this by logging in and upgrading from your subscriptions tab
Click on the "upgrade plan" text to the right of your plan name.
Next choose which plan you'd like to upgrade to. After you choose a plan you will see a breakdown of the changes, including total you'll be charged today.
To complete the upgrade click the Confirm Plan Change button, and confirm the change.
You will then be charged for the amount shown under Total Today and switched to the chosen plan!