Make your Python script or app run automatically every time you boot up your Raspbery Pi.
How to Run a Script at Boot on Raspberry Pi : Read more
How to Run a Script at Boot on Raspberry Pi : Read more
That's when you really ought to consider making it a service. See:What if you want to stop your autorunning script after your Raspberry Pi has booted? If your script has already completed running, it will be gone from memory but if it’s designed to do something continuously, you’ll need to search for and kill the task.
1. Search for your script by using the ps aux command and putting the name of your script (or at least a partial name) after grep.
...
2. Kill each process number using the sudo kill -9 command.