If you install Forte 4 (including the trial version) and then uninstall it, it will remove any existing EHCo plugin installation and you must re-install EHCo using your EHCo license key to recover it.

This is a confirmed bug and we are looking into a solution.

The problem arises because EHCo is a shared plugin, and is updated in Forte 4.  The updated version is located in the Forte 4 installation folder.  When the uninstaller runs, it unregisters EHCo as well, leaving no copy of ECHo registered (i.e. it doesn't revert to the older EHCo install still present on your system.)