The short, short version -- it's probably worth it to grab this app while it's on GOTD *IF* you routinely make advanced, difficult selections or masks in your image editing software. It has low impact on Windows & disk space, and even if your editing app generally does better than CutOut, you *might* come across an image that for some reason works better in the Franzis software.
Every time you make a selection in image editing software you're creating a mask. When you paint walls in your home, you might use masking tape, drop cloths etc. to keep the fresh paint from getting where you don't want it. Masks in image editing software do the same thing -- they make sure that whatever you're doing, it only applies to the selected part of the image. And those masks are indispensable when/if you get beyond more casual image editing, where you're doing more than just cropping, resizing, &/or adjusting the overall colors. That Does Not mean that you need CutOut or something similar -- most of the time you don't or won't need a very high degree of accuracy when you create &/or edit a mask.
Where you will need that accuracy is when you're replacing the background behind your subject, changing the color of someone's clothes or hair, if you're changing the shape or size of their body parts etc. And then you still might not need CutOut, depending on what tools you already have available. Lots of image editing apps have some sort of selection tool(s) that seek & find edges when you trace an outline close to those edges, which is basically how CutOut works, so it's mostly a matter of which app works better, with higher accuracy, & faster for you with the type of work you're doing.
No selection or masking tool will work perfectly to detect every edge of every subject exactly -- you will have to do some tweaking. A LOT depends on the image... If you zoom in far enough you'll see pixillation in every digital image, where the only straight, smooth lines are horizontal & vertical. What varies is how far you have to zoom in to see that start to happen. The higher end Nikon & Canon camera models will do immeasurably better at this than some other camera brands & most cell phones.
There's something called the ISO setting, which determines how sensitive the digital sensor [or in the old days film] is to light. The higher the setting, the less light you need to take a picture, but at a price -- the higher the ISO setting, the more noise you're introducing to the image. Some cameras add more noise at lower ISO settings than others -- you can use higher ISO settings & not suffer as much noise from some cameras [this info is included in better camera reviews].
The nature of a digital photo, unlike a biz graphic, is to have continuous tone... This means that any object edges tend to span at least a few pixels, where pixels with the object's color are interspersed with pixels of whatever color comes next in the photo. Add noise, which loosely defined means pixels that aren't either color -- they don't match either the object or its immediate background -- and finding an object's edge can become almost impossibly difficult. You can sometimes mitigate this somewhat by shrinking your selection [i.e. enlarging the mask area] by 1 - 3 pixels. Regardless, you most always want to feather your selection or mask -- feathering blends pixels with the object's color with either pixels that are transparent or have the background's colors.
Masks or selections can be saved, depending on the editing app & the file format. Importing an image with its mask into an image editing app, you most always can shrink &/or feather that mask in the editing app. Masks & selections can traditionally be viewed either as a red, semi-transparent overly, or with a "marching ants" border -- you can usually switch between the two, & there may be added viewing options.
On to the GOTD of CutOut itself, there is no universal URL for registration -- the setup routine determines what's likely a hardware ID, then adds that to the URL when you click the button to go on-line to register. Once you enter your ID & the key -- you get both in an e-mail -- the setup routine extracts the real setup file into a folder in the User Temp folder -- I normally grab this for easier, faster installs. Installation only adds files to the program's folder [~17MB], & the number of new registry entries isn't bad at all, though unlike every other Franzis app I've installed, this made no attempt to copy its plugins to the folders for image editing software. This does seem to be an app that Franzis sells but does not develop in-house -- it does not add files/folders to the User folders for example. Running the app it shows off one of my pet peeves, insisting on opening full screen, regardless of its state when you closed it. It was especially annoying [to the point I might ask for my money back if I paid] when opened for the 1st time -- with the registration window displayed, you can't reduce the size of the app's window, & you're locked out of Windows TaskBar, so you have to Alt+Tab to get to the window with your registration info. Close that registration window and the app doesn't seem to offer any way to register.