You’ll forget “exactly” how you did it. Sure.

But you’ll remember that you solved something “similar” before and know that you can trace back or use some keywords in google/bing/ddg/etc to find a blog or something that goes over it in detail. Helping you solve the issue.

If you never learn it in the first place. You’ll never know it’s there.

You can always respond like.

“Hello,

As we discussed earlier today, you will be giving me an employee contract for $XXX,XXX

Best regards. “

Then CC as many people as possible.

…

That’s how these people work, right?