Before installing a new JFS version please ensure your maintenance is active.
If it is not, JFS may stop working after upgrading and thus stop protecting your data.
Navigate to JIRA Administration → Add-ons → JFS Licensing
Inspect 'License Status' value
Value Meaning VALID Your maintenance is active. You may use the most recent JFS versions with your license. EXPIRED Your maintenance has expired. You may use JFS versions released before 'Supported Till' date only.
To renew your support and maintenance please visit 'My Account' → 'Licenses' tab
See sample screenshots below: