Launch the Lowender Registration Tool. There are two text fields here, "Name" and "Authorization Code". Copy/paste this information from the registration email that you received. As soon as you paste in the second field, the readout should change to "Your copy of Lowender has been successfully authorized."
You can use the "Check for current version" button to make sure you have the latest update of the Lowender.
Now launch your host audio application, capable of hosting VST, RTAS, or AU format plug-ins. The Lowender should appear in your host's plug-in menu.
In Pro Tools, Lowender will appear in the plug-in category of either "Other" (if using the Pluggo 3.5 version), or "Harmonic" (if using the Pluggo 3.6 version).
If Lowender does not pass any audio within your host application, you may have a registration issue. At the top of the plug-in window, there's a pop-up menu labeled "View". You can switch this to the "Registration" view to verify your authorization.
No registration is required for the demo. Every 45 seconds, the demo version will mute momentarily.