I have uncheck 21 trial box. And still no place to put register key.
The registration worked for me so I am doing this from memory now. Open the program and in the “About” menu there is something that mentions “Premium”. Click on that and a pop-up window opens. On the right side of that window it shows a “Registration Number” already filled in and below that ia a box where you input the key from here. I hope that helps some.
Thanks to POS and SOS.