Not knowing what the script or command is/was makes it harder for me to answer, but as a general rule: If nothing outstanding enough to force the Operating System to log it happened, it's pretty much lost, as far as I know.
Good software developing practices involves writing "Debug" code, which will allow the program to leave messages about its own progress somewhere, either in a text file, or in
/var/log/yourscriptname/last.log as example.
If your script contains such debugging code, those two links might be of use to you:
If there is nothing to be found, I would recommend reading the script to see if it contains debugging code, and if none is present, add something equivalent to
Script finished at [time here] where needed.