And may be translated as:
"Remember that you are mortal."
"Remember you will die."
"Remember that you must die."
"Remember your death."
This phrase names a genre of artistic creations that vary widely in medium, but which all serve the same purpose to remind people of their own mortality.
I use photography as my main means of creating my own Memento mori these days. Although I have used a wide range of other mediums to express it my entire lifetime.
My newest work is a self portrait series with my bone collection. Some of my favorites, click to see larger versions and the full set: