This cron-based code runs daily and automatically changes any user with an expired membership_expiration date from the "member" role to the "subscriber" role.

change_role_expired_memberships.php

<?php 

/**
 * Change Role for Expired Memberships
 * 
 * This cron-based code runs daily and automatically changes any user with an expired membership_expiration date from the
 * "member" role to the "subscriber" role.
 * 
 *
 * 
 * Author: Chris Eggleston
 * Version: 1.0
 * 
 *
 */
 
 // Schedule the daily expiration check if it's not already scheduled
add_action( 'wp', 'pmpro_schedule_expiration_check' );
function pmpro_schedule_expiration_check() {
    if ( ! wp_next_scheduled( 'daily_membership_expiration_check' ) ) {
        wp_schedule_event( strtotime('midnight'), 'daily', 'daily_membership_expiration_check' );
    }
}

// The actual function that runs every day
add_action( 'daily_membership_expiration_check', 'downgrade_expired_members_to_subscriber' );
function downgrade_expired_members_to_subscriber() {

    // Change these if your meta key or roles are named differently
    $expiration_meta_key = 'membership_expiration';   // the same key you save in both forms
    $paid_role           = 'member';                 // current paid role
    $free_role           = 'subscriber';             // role after expiration

    $users = get_users(); // gets ALL user IDs (very fast)

    $today = new DateTime('today'); // midnight today for accurate comparison

    foreach ( $users as $user_id ) {
        $expiration = get_user_meta( $user_id, $expiration_meta_key, true );

        // Skip if no expiration date saved
        if ( ! $expiration ) {
            continue;
        }

        try {
            $exp_date = DateTime::createFromFormat('m/d/Y', $expiration );

            // If expiration date is in the past (or today), downgrade
            if ( $exp_date && $exp_date < $today ) {

                $user = new WP_User( $user_id );

                // Only act if they actually have the paid role
                if ( in_array( $paid_role, (array) $user->roles ) ) {

                    // Remove paid role
                    $user->remove_role( $paid_role );

                    // Add free role (in case they don't have it)
                    $user->add_role( $free_role );

                    // Optional: log or send email
                    error_log("Membership expired → downgraded user ID $user_id to subscriber on " . date('Y-m-d'));
                }
            }
        } catch ( Exception $e ) {
            // Bad date format – you could clean it up here if you want
        }
    }
}