Paint Tool Sai - read license key how?

I bought the license key for Paint Tool SAI years ago and used the program on my laptop.

Now I have a new computer and of course I want to have Paint Tool SAI on it, too. However, I no longer have the license key!

Of course I do not want to buy the program again and therefore I have to somehow find the license key.

Do you know how to find out? I also find no support from Paint Tool SAI. I have a system ID and that proves that I bought the program.

Does anyone know what I can do? Can I read the license key somewhere in the data? Or who has another idea?

https://www.systemax.jp/en/sai/reissue.php

The license file will be regenerated for your hardware and bound to it as well. Just go to the manufacturer's website and enter the system ID of your new computer and download a new license file. Can you do that any number of times?