There are just some things that you like done your way. Ever since I’ve been developing with PHP, I’ve kept a file with my own custom developed functions that I know I may want to use again. Everything from a custom send email function that will report bounces back to me to simple one parameter file uploads to encryption functions and so on.
I got into the habit about ten years ago to maintain this master function file and then on every web server that I have under my control, I set the flag in the php.ini file,
auto_prepend_file to my master functions file that way all of my custom functions are available to me in every PHP file on that system without me having to do anything.