I guess install was the wrong word. I basically meant if you should
get rid of the earlier version first, to make sure there were no
compatibility issues during use.
the lammps executable is fully self-contained and does
not read any files outside of what is specified in your
input file. so once you have an executable, you don't
need the compile tree.
i would still keep it around and compile a new version
in a separate tree until you are convinced the new version
works for you.
once i go to production mode, i usually copy a specific executable
into the directory where i run the whole trajectory with the
same executable, even if there would be new ones around, except
if there is a bug being identified that affects my running
production simulation, but in that case the trajectory is
mostly useless anyways.