I think a great product demo is not about the product at all, but rather about something cool that accidentally was possible only with this product.
Remember the scene from "When Harry met Sally?" The restaurant scene? (https://youtu.be/6pQgbEEFPq0?fea...)
It ends in the famous line "I'll have what she's having" - the product here is the food order, but the demo is not about food at all.
If your demo achieves this, it is memorable.
IMO a product demo becomes memorable when it clearly showcases the unique value and benefits of the product through engaging storytelling and real-life use cases. Personal touches, like addressing specific pain points and interactive elements, also make it stand out.
In my opinion, tell a story. Weave a compelling narrative around the product's use and benefits. Directly show how the product solves common frustrations or challenges in as much direct way as possible
A memorable product demo effectively solves a real problem, engages the audience with a compelling story, and highlights key features through a clear, polished presentation.
If the product is really innovative, make the audience think: "Wow, I didn't know you could do that!"
If the product has direct competitors, make them think: "Look how easy it is to use!"
Best of luck