Extend add-on trial for Jira Datacenter
Go to my.atlassian.com and select Licenses. Find the Mobility for Jira add-on then click on New Evaluation License (see screenshot). Copy/Paste the new evaluation key into Jira/Manage Add-ons/Mobility for Jira or any other Mobility Stream product you would like to extend.
Alternatively you can reach out to Atlassian Support.
Go to https://www.atlassian.com/company/contact/purchasing-licensing#/
How can we help you? > Product Trials - Start or extend your team’s product trials
Choose a topic > Extend product trials