How long will program stay in memory without power?

Question

Let's say we program an arduino uno or nano and then stop using it for a while. How long can we expect the program to last on the arduino?

Answer 1

More than 20 years, and probably more than 100 years.

That's the guaranteed minimum:

Data retention: 20 years at 85°C/100 years at 25°C⁽¹⁾

_{(1) Reliability Qualification results show that the projected data retention failure rate is much less than 1 PPM over 20 years at 85°C or 100 years at 25°C.}

Answer 2

Practically forever. Rather make sure the contacts don't become too rusty. ( 83.7 % of Arduino problems are mechanical and contact issues :) )

Will your grandchildren still have a legacy USB cable and be interested in that thing and your c++ coding skills then?

Answer 3

upto 20 years at 85°C and upto 100 years at 25°C