The single word of ‘memory’ is used to encapsulate several concepts:
Sensory memory refers to that part of your memory directly associated with you hearing or seeing things.
Working memory is the name given to the short-term memory that is used to process and organise information captured by sensory memory. The processing capacities of both visual and verbal working memories are limited. They are easy to overload and consequently information simply does not get processed.
Long-term memory is the vault in which you hold all your previous experiences. Combining new experiences being processed by working memory with existing information from long-term memory is the key to remembering new material.
How the memory works
When you deliver a sales presentation to an audience, the graphics (usually PowerPoint slides) are seen by their eyes. The words are also seen by their eyes and listened to by their ears. All of this happens in sensory memory. What does sensory memory do? It is essentially a selection process that chooses a) what you will tune into and b) what you will ignore.
Having selected what you will pay attention to, sensory memory passes information through to working memory. Working memory seeks to organise the inbound information and creates a pictorial model and a verbal model. Those two models are brought together and understood by a process of integration and a link to prior knowledge. All prior knowledge comes from long term memory.
Is this a problem?
Working memory is very easy to overload. Too much information can cause an explosion in working memory, resulting in your presentation sales message being forgotten. If there is no integration with prior knowledge, your message will never reach long term memory and therefore stands no chance of being remembered.
One of the most important points underpinning all high-converting sales presentations is that they recognise the limited capacity of working memory and are designed to avoid overloading this part of the memorising process.
One of your goals as a presenter should be to present your material in such a way that it's easy for your audience to connect the new material with their previous experiences (resident in their long-term memory). Making this connection will help your audience remember the new material that you are presenting to them.