The paragraph below is general info for all Windows Users.
After you have made a purchase, you will have received an e-mail with a hyperlink. You click this link and it downloads your zipped-up licence to your computer. Inside the zip is the licence file, it is called "keyfile.inf". If you have followed the detailed instructions on the download page and unzipped the keyfile into the dnc4U home folder, and it still looks to you like the keyfile has not registered your software, this is for your information.
You unzipped the keyfile into the dnc4U folder, and it still says either XX days left, or it has expired and it says 0 days left.
Reasons it could show 0 days left.
You have made a typo, and you have not got the correct code. It's easily done, and it happens quite often. Click Register Software on the top menu bar. You will see this screen. (The code shown is ours - yours will be different)
If a typo is not the problem and the number is correct, then click the Unlock Folder button on this screen. This will show you where you should have unzipped the keyfile. After you click this it will pop-up this info. When you click OK, it will open up the folder for you. Please check that the keyfile is in that folder.
It often happens that users install dnc4U in a few folders, just to test it, then forget where they installed. This method will show you exactly where to put it.
This next paragraph is primarily intended for Windows Vista, Windows 7 and Windows 8 Users
With the advent of Vista, Win7 & Win8, Microsoft has commited to making security much tougher, and as a result, much more difficult to understand the labyrinthine access and security permissions. This can be a real headache, especially on corporate networks, where the IT department has been real strict with users.

One of the issues of this heightened security is that some files downloaded from the internet may be either blocked or they have insufficient access for a particular user - what this means is that our keyfile licence can be detected (because it can be seen to exist) but the information inside cannot be read, because the user has insufficient access to even read from it.
If you have installed the keyfile, as per our instructions, and you see this on your screen, where there is no value to the number of days left, then it is because the current user profile does not have sufficient access to read it.
In the first instance, you should right mouse click the keyfile from inside the dnc4U folder, select properties and unblock the file.
If unblocking the file does not work, right mouse click the keyfile from the dnc4U folder again and click the security tab. By default, the minimum access should be at least Read and Read & Execute, and in most cases this happens, and so the keyfile can be read. We have no control over the initial permissions, it is all down to inheritance on your computer system. Unless there is any overriding reason not to, we would recommend that you give users full Allow access to the file.
If your permissions show any deny for read, then this is probably the problem.
When Your Software Is Registered
When dnc4U is registered, it is easy to tell. Your company name will appear in the title bar instead of the number of days left and the menu item "Register Software" will change to About.
If you click About, you will see a small Union Jack flag in the top corner. It is then registered.