Unreal Plugin Trial Has ExpiredIt seems that the plugin is still using an older installation of Houdini than the 393 you installed.
To make sure you're using the correct plugin/Houdini version, go to:
C:\Program Files\Side Effects Software\Houdini 14.0.393\engine\unreal\4.8
and copy the HoudiniEngine folder. Now go to:
C:\Program Files\Epic Games\4.8\Engine\Plugins\Runtime
delete the HoudiniEngine folder there if it exists, and paste the folder you copied.
Now restart Unreal 4.8 and go to Edit > Project Settings, scroll down to Plugins and select Houdini Engine. In the Houdini Engine settings screen, scroll to the bottom to Plugin Information and make sure the versions there list 14.0.393.