Hello,
first of all you could have a look there そこに見てください): https://www.adobe.com/jp/account.html>>> see My productsView all >>> These registered products are associated with your Adobe ID. >>> Name >>> Serial number
If not successful (正常に実行されない場合) use http://helpx.adobe.com/jp/x-productkb/global/find-serial-number.html >>> I lost my serial number >> see comment
Good luck!
Hans-Günter