The setting for the poem 'Remember' by Christina Rossetti could be heaven, or it could be earth. The poet could have written their own epitaph to have carved on their gravestone. That would be an interesting almost metaphysical idea, as it would span space and time in that it was written in an earthly sense while the poet still existed here, yet the message would travel to the reader 'from beyond' as they read the message on a graveyard headstone. This poem is quite personal though and has the feeling that it was addressed to someone very close and special. The poet absolves the reader or special person from all guilt at the odd forgetful moment, wanting them to be happy, not sad, and think joyfully of them.
The poem, "Remember" by Christina Rossetti, is set as the narrator is in the process of passing on or possible the poem is spoken as a missive from the afterlife. Clearly the narrator is not expecting a response from the receiver of the spoken words. The author has left no indication that this is meant to be a conversation. So one can only assume since the majority of the poem is giving instructions as to how the narrator wants to be remembered after s/he passes, that it is either a deathbed declaration or a missive from the afterlife. I can envision the departing soul murmuring these words as it hovers over those gathered around the bed of the dying person.