When you install YOOtheme Elements, you'll see a message in the Joomla dashboard saying the download key is missing.

You need this Download Key to enable automatic updates. The update check verifies that your Download Key is valid and that your subscription is active.

You can find your personal Download Key on your account page:

https://www.joomill-extensions.com/account/downloadkey

Copy the Download Key and paste it into the Edit Update Site screen.

Click Save and Close when you're done.