systemd service stop working after sometime

Hello supporters,
I’m running one python script using systemd service.
i have observed that sometimes it works fine .sometimes it stops working after sometime.
sometime it doesn’t work at all from startup.
i mean how do i make sure that it’s working or not and it is like
the python script is MQTT client script so sometimes it stops responding after sometime
sometime it stops responding from startup so i 'm not able to figure out what is the issue.
please help me for the same