The support and maintenance package includes:
The first year of support and maintenance package is free. When it expires and you want support, or want to upgrade to a new version, you will need to renew your subscription. Price depends upon the license you have purchased. Please see our pricing page for details.
What if I choose not to extend my support and maintenance package?
You don't have to extend your support and maintenance package. KBPublisher will still work for you. All it means is that you continue to use the version you purchased. You cannot upgrade (except for minor versions) and you will not get the same level of support.
Please clarify what you mean when you say "Even when your support and maintenance package runs out, you can still upgrade minor releases for your major release"
Suppose you bought KBPublisher version 3.0. That was the major release. You've had it for 18 months now, and you let the support and maintenance period run out. Then we go ahead and release 3.0.1. Even though your maintenance package has run out, you can still upload and install release 3.0.1.
You can only get minor release upgrades for your current version. If you are using release 3.0 and are out of the support period, then you can only upgrade to releases 3.0.x. You cannot upgrade to, say, release 3.5.1 (unless you extended your support and maintenance package first.
Major versions implement new functionality. Minor versions are for fixes and small tweaks to the system.