When you download the viewer and install it, you get a program which can operate as either a free viewer or an advanced viewer. The advanced viewing is enabled when a license is installed.
Anyone can go to the website and upgrade to the latest version. So everyone gets any program fixes. But the enhancements in each release are only enabled for users with maintenance through the date of the release. For release 2.5, that date was September 1, 2010. When you renew your maintenance, the enhancements will be enabled.
To renew your maintenance, please contact Lori at (303)963-5388. She'll be happy to take care of it for you.