So essentially what I would like to know is if this is even possible. I use my wordpress site to promote free Kindle books, which are free for up to 5 days.
At the moment I use Gravity Forms to automatically post the freebie posts but I still have to go in and 'archive' them once they are no longer free. This is a tedious task that I would pretty much do anything to automate.
Now, I don't need the actual content of the post to change at all - just the post category to automatically change after 5 days. So, anything posted using that gravity form would automatically change to the 'books' category after 5 days.
Is this possible? What kind of script would I use to make this happen? Would it be a Wordpress edit or a gravity forms edit? I most likely will have someone do it, and if you want to do it, feel free, but right now I am simply asking if it is even possible and to get a basic understanding of how to go about it.
This is possible and is a job for WordPress Cron. You'd schedule your event to run every day using wp_schedule_event. When it runs, it will call your function that 1) checks for posts that were created 5 days ago and 2) changes the category on those posts.
And if you don't get traffic to your site every day (the WordPress Cron only runs when you have visitors to your site), you will need to create an actual system cron on your server instead. You can use the WP-Cron Control plugin or follow the instructions in Tom McFarlin's article.