Pamiętaj o śmierci, is more so the original quote to the original phrase
Memento mori is a Latin phrase translated as "Remember your mortality", "Remember you must die" or "Remember you will die"en.wikipedia.org/wiki/Memento_mori
Pamiętaj o śmierci is fixed phrase
unfortunately chosen
even despite wiki
pamietaj że umrzesz (remember you will die) or
pamiętaj umrzeć (remember to die) sounds better
than pamiętaj o śmierci