Need PHP Script Modified

I have a 1 page script that imports businesses into wordpress. Problem is i'm getting a memory error half way through the complete import so I need the script to inject that last post ID imported into a TXT file and continue where left off later when I re-run the script. the script already counts the total posts and appllies an ID so all it needs is to basically mark where it gets the error and continue when i restart it. pretty simple, just above my head.