auto block post on premium-post category for 5 days

add_filter( 'jeg_metabox', 'j_override_paywall_block', 99, 2 );

function j_override_paywall_block( $default, $name ) {
    if ( 'jnews_paywall_metabox.enable_premium_post' === $name ) {
        if ( has_category( 'premium-post' ) && is_post_older_than_5_days() ) { /* change premium-post with your Premium Post category slug */
            return true;
        }
    }
    return $default;
}

function is_post_older_than_5_days() {
    $published_date = get_the_date( 'U', get_the_ID() );
    $current_date   = current_time( 'timestamp' );
    $diff_in_days   = ( $current_date - $published_date ) / DAY_IN_SECONDS;
    return $diff_in_days > 5; /*  check if more than 5 day published */
}