You can purchasing a full license to Wii Transfer on the Riverfold web site using PayPal. You will be prompted to confirm the transaction by logging in to PayPal. You should receive two emails as soon as the purchase is complete: the first is a receipt from PayPal for your records; the second is an automated email from Riverfold with your serial number.
To unlock the full Wii Transfer functionality, choose Wii Transfer → Registration and paste in your serial number, then click Register. That's it! There is no need to restart the application.
If you hear a beep instead of Wii Transfer accepting the serial number, double-check that you have pasted or typed the serial number correctly. Both uppercase and lowercase letters are treated the same, and whitespace should be ignored. If you continue to have problems please email support@riverfold.com.
There is also a "family pack" available which includes 5 serial numbers. You can use these serial numbers to register separate copies of Wii Transfer on up to 5 computers in your household. This package is designed to make Wii Transfer more afforable, so please do not share these serial numbers with anyone outside your household.
Note about delays: If you don't receive the serial number email within 10 minutes after purchasing, make sure the email address on file with PayPal correctly matches the email account you are checking. If it does not, or if there were other mail server delays outside of Riverfold's control, please email support@riverfold.com to request the serial number be sent to a different email address.