Translation:
I purchased it in the product version before and used it, but the app disappeared by a hand.
I looked for the product I bought, but I couldn't find it. However, the product key is ready to be confirmed.
In this case, I bought it before, but can't I use the product key anymore?
Does that mean you can't download the Power Director and use your old product key from there?

Reply in English:
You can check your computer download folder to see if you still have those downloaded files.
You can contact support here and ask for a new download link for your version of PowerDirector. Be sure to give your purchase receipt information: https://jp.cyberlink.com/support/index.html .

日本語で返信:
ダウンロードしたファイルがまだ残っているかどうかは、コンピュータのダウンロード フォルダを確認できます。
サポートに連絡して、お使いの PowerDirector のバージョンの新しいダウンロード リンクを求めることができます。必ず購入領収書の情報を提供してください: https://jp.cyberlink.com/support/index.html。