The whole settings of phpEd's are located in Windows registry, I have exported from registry mine settings, and successfully using as a backup. Still such feauture should be implemented, because there is no normal settings backup and restore feauture implemented.
If you want to backup your phpEd's settings from registry, use: Win + R -> type 'regedit' -> in registry tree view open HKEY_CURRENT_USER -> Software -> NuSphere -> PhpED4.x. Select this folder in tree view, press right mouse button to open contextual menu and choose 'Export', save this file to your safe location. Next time, when you (re)install phpEd, after setup, double click this exported registry file, and you'll get most of this IDE settings back

(including phpEd's serial number).
Cheers
