How to call inside the theme

if you want to put a product in a template page, you can use the do_shortcode method like so:

<?php echo do_shortcode('[AMAZONPRODUCTS ASIN=1234567890]');?>

or if you used a custom field for the ASIN, you could do something like this:

<?php
$amazon_prod = get_post_meta{$post->ID,'amazon-asin',true);
if($amazon_prod!=''){
    echo do_shortcode("[AMAZONPRODUCTS ASIN={$amazon_prod}]");
}
?>

Hope that helps.
Regards,
Don