Canonical is no stranger to support. With every LTS release of Ubuntu, you get 5 years of standard support (which includes all packages found in the main Ubuntu repository).

If that's not enough, you can subscribe to Ubuntu Pro to gain another 5 years of security support along with support for apps within both the main and universe repositories.

It gets better.

Canonical has just announced they've added Legacy Support, which expands long-term support to a whopping 12 years for all distributions starting back to version 14.04. This is especially important to businesses who've deployed systems and need to depend on them for years.

To that, the official release announcement states, "Running the latest operating system (OS) offers new features and enhanced performance, which is a good choice for new deployments. However, for large, established production systems, the transition to a new OS version presents a challenge as it may involve updating the entire software stack running on top of it. This complexity is amplified by modern software architectures that incorporate containerisation, microservices, extensive data management features, as well as integration with third-party APIs."

The one catch to the new Legacy Support is that it is an add-on and, from the way the release reads, it's not going to be free. There's no mention of the Legacy Support add-on within the Ubuntu Support page, so it's hard to say what the price will be.

You can always use the Contact Us form to find out what the price will be, or wait until the official announcement.