This is "Provide Some Answers," which is a feature where long unresolved plot points are eventually resolved.
Reader Jaime B. wrote in to suggest that I address the big plot point in last week's Amazing Spider-Man, which resolved a plot point from J. Michael Straczynski.
I've done a Left Unresolved on this one in the past, and I'll mostly just repeat that post here.
In Amazing Spider-Man #503 (by J. Michael Straczynski, Fiona Avery, John Romita Jr. and Scott Hanna), Spider-Man runs afoul of a powerful being known as Morwen, who has possessed a young woman. At the end, Spider-Man encounters Loki, who is searching for Morwen, as well....
They take down Morwen, as Spidey discovers that Loki is invested because the young woman who was possessed was Loki's daughter (she doesn't know that she is Loki's daughter).
In the end, they save her and Loki then says he owes him a favor...
And that was it. During "One More Day," when Spider-Man was desperate to save Aunt May's life, Loki was then "dead," so he couldn't help Spider-Man at that point. Dan Slott once joked that the favor had been paid off off-panel when Loki helped Spider-Man move a couch once.
However, Slott actually DID decide to resolve the plot, once and for all, in last week's Amazing Spider-Man #795, almost THREE HUNDRED issues later (granted, Amazing Spider-Man went thrice-monthly for quite a while there, but hey, hundreds of issues is still hundreds of issues, ya know?)