Wordpress function change user role

I need a quick function, for wordpress. I already have a function that hooks into woocommerce and changes user role from author to editor once user buys a product, I want it to reverse user back to author after 30 days. It will send user an email on the 23rd day as a reminder and on the 27th day also. So the easy way to do this is to check if user has been an editor for up to 23 days - send email, I user has been an editor for up to 27days send email, finally if user has been an editor for up to 30days change user role to author and send a final notice to user.