You have had really excellent dreams, that you were truly pissed off to be awakened from by some fool or some cursed alarm clock. You have also had nightmares, which made you wake up in a cold swaet, grateful that you were able to awaken.
So, you know that dreams get pretty real, and approximate reality as you know it to near perfection, if not absolute perfection.
What does all this mean, the ability to create a reality and exist in it, out of your imagination and your store of memories?
You have to consider the properties of the stage the dream is played out on.
When you die, there will be no change in gravity whatsoever. The gravity of your individual energy packets, the atoms they make up, the planet those atoms help make up, the universe the planet helps make up, none of the gravity associated with any of that will change in the slightest.
Has your consultant figured out yet what has kept your memories alive so far, stored on gravity as they must be?
Memories are stored on gravity. People have lived to be 120 years old and retained their memory. Therefore, considering that memory is stored on gravity and that gravity does not change in any way when you die, if you die when you are 20, your spirit is certain to live for at least another 100 years.
This is why Hiroshima and Nagasaki survivors are proof of life after death, and not proof of eternal life. There is no way to prove eternal life.
Hoever, gravity does tend to be a very long lived phenomenon, lasting for a period of time far beyond the capacity of mere mortals to be able to consider.
Of course, there are a number of permanent attributes to the universe, or at least permanent as we can comprehend it. The laws of physics might be an example of memory. The speed of light being a constant, or the mass of an electron being a constant, or maybe Bode's law, might be examples of some form of memory. These might change over time, but would take such a long time to change that we could never hope to live long enough to measure it.
Since there is no immediately rational or logical or scientific explanation as to why gravity can store memory, it would be absurd to consider what the upper limit of the duration of the storage might be.
If memory can be stored for 120 years on gravity, that does not remotely indicate what such an upper limit might be. A statistician might say to examine the lifespan of galaxies, the longest-lived phenomenon ever witnessed and measured by man, and take 120 years, and if there is a limit to the number of years one's spirit and memories can exist, stored on gravity, is likely to be, by statistics alone, somewhere between those two, more likely closer to the midpoint than to either end.
Suffice it to say, that science can only estimate, and the estimate of science is a number measured in billions of years.
It isn't even close to likely that it is a short period of time. The memories could well be stored until the end of time, and your spirit could last just as long.