Adobe provides free upgrades for versions that based on the product purchased. For example there were several updates to CS5 and those were free. But CS6 is a major core change.
As mentioned, ViewNX comes with the camera and does an excellent job of rendering the raw files and a version can be saved in TIFF or JPG that any editor can handle. You are probably better off doing that extra step, I have found that any new model is rendered better in Nikon software better than Adobe so I keep both up to date. You can also try the free 2 month trial of Capture NX2 as a full editing option to see if you like it. Both ViewNX and CaptureNX have the advantage of being able to read the camera settings so the rendered NEF raw file will start out looking like the jpg so you start with an image that needs less work than when opening the same file in Lightroom or PS CS6.
There are also free raw converters besides the low cost alternatives to Adobe and Nikon software. One that is popular is RawTherapee. a new version( 4.0.10) will be out in a few days. Get it for free at http://rawtherapee.com/downloads