Sudoktor is distributed as Shareware. If you like the program and wish to continue using it, you should register it. Registering will give you access, without the demo limitations, to all the functions of Sudoktor.

You'll be able to handle more than 20 puzzles in a session.
All the Analysis options will be available in the same time.
The "nag" dialog will no longer be displayed each time Sudoktor is launched or you start a new puzzle.

Registering will also allow you:

to have access to all of the versions of Sudoktor on any platform (Windows, MacOS, iPhone, Pocket PC) with the same personal password.
to take advantage of the frequently released updates which are provided free of charge
and last, but certainly not least, to encourage the author to continue development of the software.

Entering your password:

When you have received your password following registration:

Follow  the instructions you received with your registration code.
Click on the "Register" button. Type your user name (being careful to respect the use of upper and lower case characters) and your personal key code in the "Registration" dialog.

If the registration process is successful, the key turns the demo version into a complete version.

Make sure to keep a copy of your registration key in a safe place (preferably NOT on your computer. If you should lose it, the registrar for your region keeps a record of it. Just contact him by e-mail.