This one pains me.
When you say you’re going to do something, like send a review unit, do it.
If you forget you said you were going to send a unit, and you pitch me again a month later, and I remind you of our conversation, and you say, sorry, I’ll really send it this time, then really send it.
If, a month after that, having neither sent the product nor checked in, you pitch me again as if we’ve never spoken, you do not get to say, when I remind you of our first and second conversations, “I requested a sample and am sorry to hear it did not arrive.”
There is no recovery from this.