If you see a Killed or a RETCODE=137 message in /var/log/allsky.log, there's a good chance you need to increase the amount of swap space you Pi has. It's easy to do:

    systemctl stop allsky
    allsky-config  recheck_swap
    systemctl start allsky

> The swap file cannot be in use when increasing it, so make sure you don't try to increase it when a timelapse or another memory-intensive command is being run.

If you are still having problems, try increasing swap size to 2048 MB or even 4096 MB.

A more detailed description of how to manually increase swap space, including adding multiple swap files, is here.