WHAT DOES IT MEAN FOR MEMORY IF YOUR SENSE OF SMELL FADES?

A diminished sense of smell can often just be a sign that someone is getting older. You may also have a deviated septum, a sinus infection, nasal polyps, a cold, or the flu. However, it can also be a symptom of a memory loss-related condition, like Alzheimer’s or Parkinson’s disease. 
Source: Smells and your memory (ceenta.com)

Other sources: The connection between smells and memory - SeniorsMatter