You get an idea for a poem or a story, but you're in your car or out walking, somewhere impossible to write. And the idea spins into lines in your head, begging to be recorded. You worry that you'll forget this windfall of words before you can write them down. My advice to you: Don't strain to record them later if they were but temporary traveling partners. You wouldn't try to force a friendship with someone you met on the road unless some surprising, special bond had occurred. The same applies to your words.
I have learned to trust the power of reverberation in my writing life.
Reverberation is a quality directly proportional to the quality of the words. Great words tend to stick around and echo in your head till they're recorded. They are memorable because, by definition, they are "able to be remembered"--by the author as well as the reader. If you've forgotten your own words, chances are that someone else will forget them, too.
Trust the power of reverberation, and recognize that memorable words flow--they can never be manufactured.