When the bread has been sacralized (sanctified), it is no longer for nutrition of the physical body, but for the nourishment of “the souls of all those who partake of it.” It is also a reminder of one of the two elements of the Atonement, the physical body. Thus, the bread becomes the symbolic remembrance of the Atonement’s reversal of physical death.
The covenant is “to remember.” Remembering as a simple mental action is not the type of remembering required here, but it is a remembering that invokes action. In this case, the action of keeping “his commandments which he had given them.”