To work on OpKey - Desktop, you always need license for it. Whenever you install OpKey, License window will prompt up. You need to provide License in OpKey Auth, OpKey Execution Agent and Plugins. But, Personal version of OpKey doesn't need any license which is available with limited features.
For detailed information on OpKey Licensing, please refer : https://opkey.crestechglobal.com/user-guide/pages.php?subid=69&accordid=3