Nagios XI does not provide "free" license keys in the sense of a crack or bypass, but there are legitimate ways to use the software for free:
If you're looking for a free or low-cost alternative to Nagios XI, here are some options: nagios xi license key free
It is self-supported ; you won’t have access to direct technical support but can use the Nagios Community Forums . Nagios XI does not provide "free" license keys