You can upgrade your active Elementor Pro license through your Elementor account. When upgrading, you will only need to pay for the difference between your current license and the one you are upgrading to, based on a prorated price, depending upon how much time is left on your current subscription.
How to upgrade?
1. Go to my.elementor.com and log in to your account and click Subscriptions
2. Click on Upgrade
3. Enter your payment details.
4. Your license will immediately be upgraded.
If you upgrade from Personal to Plus, you’ll be able to add Elementor Pro to 3 sites instead of 1. If you upgrade from Plus to Expert, you’ll be able to add Elementor Pro to up to 1000 sites.
After upgrading, you’ll enjoy updates, support, and access to the premium template library (starting from the date you upgraded).