Ubuntu 14.04 LTS is already EOL, Ubuntu 14.04 ESM has already started it's life.
This is a follow-up to the Extended Support warning sent a month ago
to confirm that as of April 25, 2019, Ubuntu 14.04 LTS basic support
has ended. No more package updates[1] will be accepted to the 14.04
primary archive, and any subsequent support will be done via Extended
Security Maintenance. Over the coming weeks, various images will be
archived, and the primary archive will be copied to old-releases.
Again, we remind you that for customers who can’t upgrade to 16.04 or
later immediately, Canonical offers Extended Security Support for
14.04 LTS to Ubuntu Advantage customers, more info about which can be found here:
Ubuntu 14.04 will transition to Extended Security Maintenance (ESM) on
Thursday, April 25th, 2019.
https://fridge.ubuntu.com/2019/05/02/ubuntu-14-04-trusty-tahr-reached-end-of-life-on-april-25-2019-esm-available/
Also Ubuntu 14.04.6 was released on 8-March-2019, so your 14.04.5 hasn't been upgraded in awhile so I'd suggest taking note more carefully of your system(s); this upgrade didn't require re-install, just a apt full-upgrade
https://fridge.ubuntu.com/2019/03/08/ubuntu-14-04-6-lts-released/
Please note LTS support ended for 14.04 LTS on the date in "End of Standard Support" column, the "End of Life" section includes the ESM (extended security maintenance) which is covered later in the page. It is this bit of information that has probably confused you. ESM support requires payment, and signing up for Ubuntu Advantage with Canonical.