Show post date modification

acme_mod_date.php

// Get last posted or modified date
function acme_mod_date( $postId ) {

	$posted = get_the_time( 'U', $postId );
	$modified = get_the_modified_time( 'U', $postId );
	
	if ( $modified >= ( $posted + 7890000 ) ) { // 3 months
		return '<time class="updated" datetime="' . get_the_modified_time( 'Y-m-d', $postId ) . '"> Updated on ' . get_the_modified_time( get_option( 'date_format' ), $postId ) . '</time>';
	}
	else {
		return '<time class="published" datetime="' . get_the_time( 'Y-m-d', $postId ) . '"> Posted on ' . get_the_time( get_option( 'date_format' ), $postId ) . '</time>';
	}
	 
}