I have a valid license installed. Why do I see Structure as Unlicensed or having Action Required in the Plugin Manager?
That may be so because Plugin Manager is not aware of ALM Works licenses. To verify the true status of your Structure license, please check Administration | Structure | License Details page. If it shows you that the license is OK, you can safely ignore the status of the Structure license in Plugin Manager.
Structure supports two kinds of licenses — purchased via Atlassian and issued by ALM Works. For details, please see Setting Up Structure License.