If you are seeing above error, there are 3 reasons:

  1. You haven't added your license key yet.
  2. Your license key has been disabled.
  3. Your license key has expired.

Here is the solution if you are having the first issue.

Go to Appearance >> Theme License

Check carefully if you have added the license key or not.

Here are the steps to add the license key.

https://help.affiliatebooster.com/article/8-how-to-install-affiliatebooster-theme

If your license key is not working, you can contact the support here.