You can create custom php.ini with required memory limit in your account
but that should be within limit if his script require more than 500mb then its upgrade for sure. Please follow the given steps to increase PHP memory.
1. Login to the cPanel.
2. Find the File Manager in File section of the Cpanel.
3.Navigate to the directory where you will either save or edit the PHP.INI file and then select the file and use the Code Editor. To open the file, you can click on it to select the file and then click on the Code Editor icon in the menu bar of the File Manager. You can also right-click with your mouse and select Code Editor from the menu that appears.
4. add code >> memory_limit = 64M
5. Click on SAVE CHANGES in the top right hand corner in order to save your modifications or additions to the file.
