If a customer wants to use cronjobs they need to add the php.ini in the cron command:
/usr/local/bin/php -c /usr/local/directadmin/data/users/accountname/php/php.ini /home/accountname/domains/domainname/public_html/filetocron.php
Note: The above command is related with Directadmin. You can adjust the command accordingly to your control panel and server settings.