Go to the official GFI website (or the legacy Kerio.com download archive). Choose the version compatible with your platform:

: Trial keys unlock features like the Kerio Antivirus module and web content filtering that are not available in the unregistered version. New Customers Only

These are not identical to Kerio Control but provide similar UTM features at zero software cost.

: Registering your trial key entitles you to free technical assistance from Kerio for the duration of the 30-day evaluation period.