You will see your all license keys here https://www.pickplugins.com/my-account/license-keys/

to activate auto-update plugin you need to copy correct license key and paste on settings page license key field and then save the settings.

View post on imgur.com

 

You are done, as long as your license key is active and valid it will automatically connect to our server and check plugin update and if new version update found you will update notice on plugin page.