It's not your last good idea
If you've got one good idea, there's a pretty good indication that you can come up with another. I've done it - especially when I thought someone had stolen my idea. And so can you. You've got to have more than one good idea. Once is not enough.
There is no such thing as bad memory
You can remember anything... if you're interested in it. Nobody expects you to always remember the names of everyone you meet in business. Write down the details of your customers and include them on your database system or contact manager... and look them up immediately before your next visit. You will fast become known as someone with a great memory.