Add new unit file

/etc/systemd/system/picam.service

[Unit]
Description=Picam Server

[Service]
ExecStart=/home/pi/picam/bin/python3 /home/pi/rpi-camera-zero/picam.py

[Install]
WantedBy=multi-user.target

Enable

sudo systemctl enable picam

Start

sudo systemctl start picam

Status

sudo systemctl status picam