Is it possible to retrieve my registration key?

Dear Developers,

I have bought listary pro last year and recently I recently encountered a terrible system crash and lost all my data, including registration key of listary pro. Is it possbile to retrieve my key? Should I provide my purchase certification?

Thanks in advance.

Yi

Did you search in your e-mail? Look for an e-mail called “Your Listary Pro License” from ‏"Listary Support" mailer@fastspring.com (that’s what mine is).

Yeah, but he just stated that he lost all data, including emails!