When you have not registered yet, then in the window's bar you will see 'unregistered (limited) version'.
To register, click main menu item Help - Register!
The following window opens, where you should enter the Name and Key that belong to your personal license. The name is key sensitive and any blank spaces do count!
You will be informed when the procedure has finished correctly.
This ends your registration. You can now enter Notes, Sheets, Relations and Attachments unlimitedly!