I would start by reviewing the Smartbear documentation [here], which will guide you through the process based on the type of license you have. You can log into your Smartbear license manager using this link https://manage.smartbear.com/ to see what type of license you have and if there are any concurrent users. Additionally, you can open the Smartbear License Manager tool (.exe) to move or deactivate the license locally on the machine where TestComplete is installed.
This may also depend on what version of TC you are using, there was a recent bug fix in v14.73 that fixed a related issue of TC failing to access the license after the computer was rebooted. Here's there reference: https://support.smartbear.com/testcomplete/docs/general-info/version-history/bugs-fixed-in-ver-14-73.html?sbsearch=cloned%20license
