This program is described by author as “Still it is an excellent example of how a program can be designed that is extremely flexible and powerful.”
Personally I wouldn't call a program with a very terse documentation “excellent”.
The license is wrong
The license definition is wrong.
"Free To Use But Restricted" means that the software
is free but restricted in someway. Bugzero (according
to its "pricing" page) doesn't allow restricted use
The restriction to just 5 users isn't a restriction for any
serious bugzilla-alike system. The number of 5 users
and 100 errors effectivelly disallows any serious work.
This is just a demo and yes, the demo is free.
I think the license should be
"Other/Proprietary License with Free Trial".