tbh I don't remember how I initially found out how the key is stored.
But it's inside the exe file, for NDNL (and Shokusou Tenshi Serika 2) near the string "licensetext".
In vscode it would look like this:
View attachment 4013527
If you open it with "Japanese (Shift JIS)" as encoding you could also search for "暗号キーエラー:キーが短すぎます!":
View attachment 4013583
For the decryption and extraction you can use a tool like
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.
Before you extract a file with UniExtract either create a "passwords.txt" or use "Edit -> Password List" and throw the Key into the file.
For the game you mentioned you could also use the tools as described here:
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