For server apps, you can extend your app trial up to 5 times - in other words, for up to six months.
Extend your trial by generating a new evaluation license key from Atlassian Marketplace.
Follow these steps
Navigate to Manage Add-ons in the JIRA Administration.
Find the Agile User Story Mapping for Jira plugin.
Delete the existing licence key.
Click the Free Trial button.
You should now have a new trial license for 30 days.