Reviews from people who buy direct

If a reader who buys directly from me at an event (for example), wants to leave a review on Amazon, is there certain verbiage they are supposed to use so their review won’t get deleted since it isn’t a verified purchase?

Llike how beta readers say, “I received an advanced reader copy and I’m not being compensated for my review.”

I know I can direct them to Goodreads but since it’s more likely people will already have an Amazon account, it’s less friction for them to try to leave a review there.

Thanks!