To enable or disable automatic pet summoning, press "ESC."
This will open the Options Panel; click on "Option."
In the Option selection, click on "GAME."
Look for the option to enable or disable automatic summoning, as shown in the image above.
After that, you no longer need to worry about your pet. It will always be active. If you want to turn off automatic summoning, follow the same steps above and uncheck the box.