After you buy SeeYou registration key you will get something like this:

Serial:14123, Key:XXXX-YYYY-ZZZZZ, Registered to:Andrej Kolar, for SeeYou 4

You have to compile this information into the SeeYou registration window. Please note that "Registration name" is your name as written in the key, Registration key is the part which is separated by dashes "XXXX-YYYY-ZZZZZ". Feel free to copy and paste the name and key to SeeYou in order to avoid typing errors:

After pressing the "Register" button you should receive a thank you message and a confirmation that the registration was successful.