1. Stop "Kerio Connect" service.
2. Copy "mailserver.exe" to you installation folder and overwrite it.
3. Copy "avir_bitdefender.dll" to "\plugins\avserver\Avirs" inside your installation folder and overwrite it.
4. Copy "commonWizard.min.js" to "\web\admin\init" inside your installation folder and overwrite it.
Note: This gives you the "unregistered trial" option back.
5. Start the service and apply your license.