The TrayDay Fingerprint is a code related to your computer configuration, and will be used in the construction of your registration code for TrayDay v7.
 

You can find it by running TrayDay v7, right-clicking the date icon in the tray, and selecting Register. At the top right of the resulting dialog you will see a code similar to XXXX-XXXX, where X is a number or letter. You can highlight the code with your mouse and press Ctrl-C to copy it.
 
The TrayDay license allows personal use of TrayDay on one or two computers. If you wish to install TrayDay v7 on a second computer, please include the Fingerprint for it in the "Additional information" field. Alternatively you can request this by email later if you wish.