Click the admin drop-down and choose Atlassian Marketplace and the Manage add-ons screen loads. Tip: Use Keyboard Shortcut instead: g+g and start typing manage... .
Click Find new add-ons on the left-hand side of the page and locate Notification Assistant via search. The appropriate add-on version will appear in the search results.
Click Try free to begin a new trial or Buy now to purchase a license for Notification Assistant. You'll be prompted to log into My.Atlassian.com. Once logged in, Notification Assistant will begin to download.
Enter your information and click Generate license when redirected to My.Atlassian.com.
Click Apply license. If you're using an older version of the Universal Plugin Manager (UPM), you can copy and paste the license into your JIRA instance.
Find the Notification Assistant for JIRA
Login to JIRA with administrative rights and locate the Notification Assistant:
Choose the administration cog then "Add-ons"
Locate the plugin on the left side, or within the listing:
Updating Notification Assistant
Follow the same steps as above for updating Notification Assistant, since the old add-on version is removed from the file system, as described in the JIRA documentation on Updating Add-ons.