According to Wikipedia, Memento mori may be translated as "Remember that you will die.", a warning that is applicable to human throughout our history.
However, many people such as these people are working on making death unnecessary. Hopefully, we will live long enough for their research to be practical. After that we can wait for brain state backup technologies and escape from our mortal flesh eventually.
On a slightly related note, one speculation that tries to explain the Fermi's Paradox is that the aliens already uploaded their mind to other computational substrate and don't care so much to contact primitive technological societies like ours. The uploaded minds might use little energy, can be transmitted at the speed of light, can exploit computational capacity of complex systems found in the universe, and can run at much higher speed than biological hardware, making their subjective time much faster. Due to this time scale difference, their conversation with us might be similar to our conversation with a tree.
