If you previously had installed Lowender for Pluggo on your system, you may now remove the Lowender plug-in file from:
/Library/Audio/Plug-Ins/VST/Pluggo/
However, it won't hurt anything to leave the Pluggo version of Lowender installed, and you can run the Pluggo and native versions side-by-side if you wish.
You will need to authorize Lowender again, even if you had previously done so. If you have lost your authorization info, you can request it again after logging in to the User Area of the reFuse Software site.