I'm unclear whether ESM (Extended Security Maintenance) for Ubuntu is actually free for personal use, or is it always a paid solution?
Since November 2019, Canonical has stated that Ubuntu ESM is now available for free for personal use, though it is up to three machine.
Canonical is happy to announce that all community users are entitled to a free Ubuntu Advantage for Infrastructure account for access to Extended Security Maintenance (ESM) and Kernel Livepatch* for Ubuntu 14.04 LTS (Trusty Tahr) for up to three machines, and up to 50 machines for all official Ubuntu Members.
You can get started here → https://ubuntu.com/esm
I guess the answer is on the ESM website:
Canonical provides Ubuntu Advantage Essential subscriptions, which include ESM, free of charge for individuals on up to 3 machines. For our community of Ubuntu members we will gladly increase that to 50 machines. Your personal subscription will also cover Livepatch, FIPS and CIS hardening tools.
So, it's free for personal use. And paid for other cases.