Sharpener Pro is a piece of software to sharpen the photos just before printing/publishing. Different formats require different types or levels of sharpening. As you can imagine a 4x6 image requires different sharpening parameters than a life size poster.
Nik Software provides the tool for doing this relatively easy. Custom user pre-sets can be made. So you've got easy access to the settings you use most.
After making Nik Color Efex Pro and Siver Efex Pro Lightroom compatible, Nik Software released an Adobe Lightroom compatible version of Nik Sharpener Pro (which also works like the 'old' Photoshop plugin). Just as the other two pieces of software this one is also an update which can be downloaded from the Nik website.
After installing the software, a name and serial number are required. Just use the serial number of your original (v3.0) software to register the software.