Hello Flavio,
in addition to Rave's hint, you too could have a look there: https://www.adobe.com/account.html >>> see My productsView all >>> These registered products are associated with your Adobe ID. >>> Name >>> Serial number.
If not successful use - as said above - http://helpx.adobe.com/x-productkb/global/find-serial-number.html >>> I lost my serial number >> see comment
The last time Adobe suggests so too this Contact Customer Care
Good luck!
Hans-Günter