mypmpro-give-back-level-after-cancelling.php

<?php //do not copy

// Store the old levels before the change.
function pmpro_store_old_levels( $level_id, $user_id ) {

    $old_level_we_want_to_remember = 7;

    // Store the current level in a static variable.
    $current_level = pmpro_getMembershipLevelForUser( $user_id );
    if ( ! empty( $current_level ) && $current_level === $old_level_we_want_to_remember ) { 
        // Save in a global so the next function can access it.
        $GLOBALS['stored_old_level'] = $current_level;
    }
}
add_action( 'pmpro_before_change_membership_level', 'pmpro_store_old_levels', 10, 2 );

// Use the stored level after the change.
function pmpro_after_change_membership_level_default_level( $level_id, $user_id ) {

    $level_we_want_to_give_back = 7;
    
    // If user is cancelling (level 0), and we have stored data
    if ( $level_id == 0 && ! empty( $GLOBALS['stored_old_level'] ) ) {
        $old_level = $GLOBALS['stored_old_level'];
        // Assign default level
        pmpro_changeMembershipLevel( $level_we_want_to_give_back, $user_id );

    }
}
add_action( 'pmpro_after_change_membership_level', 'pmpro_after_change_membership_level_default_level', 10, 2 );