The Success or Failure of BookSetKey

General
1

Since BookSetKey does not return any value, we cannot tell whether the key is valid or not. How can we detect that the key has been changed?

2

Please set the key, make a Excel file and see if you get the watermark.

Only copy & paste the key from the email you receive after purchase.

3

I understand that. However, I would like the program to detect this condition at startup and exit immediately, as I prefer not to let it continue running with an incorrect key state.

Only copy & paste the key from the email you receive after purchase.

I sometimes forget.

Regards.