The events in "The Cask of Amontillado" happen long before it is narrated. What does this tell you about the effect of the crime on Montresor?
I assume that the "crime" you are talking about is Montresor's murder of Fortunato. We are told that this crime happened something like 50 years before Montresor is telling us this story. To me, this shows that the crime had a great impact on Montresor. I say this because he remembers it so clearly even after so long.
You could say that Montresor was not affected much because he had a good life after he killed Fortunato. He doesn't seem to have been driven crazy by guilt. However, I think it is more appropriate to say that it did have an impact. I'm not yet 50, but the things that I remember in detail from 20 or 30 years ago are typically ones that had a large impact on me. So I assume it is the same with Montresor.
it shows that the narrator never had forgotten the bad effect of what fortunato had done to him.
from the first paragraph of the story he tells the depth of the injury he has.
the thousand injuries of Fortunato i had borne as i best could; but when he ventured upon insult, i vowed revenge.