Stellar Phoenix JPEG Repair has a very simple and user-friendly interface that helps you repair photographs or image files that have been corrupted.
On launching the program, you get a window as shown below:
Under Tools menu, find the option Register - use it to activate the software.
The registration window is displayed. If you have purchased the product and received the registration key select 'I have a key to register the product' option. Click OK. In the Registration Key box, type the key. Click OK.