woocommerce download post-types\writepanels limits?

It is possible to intercept the get_post_meta('_download_limit') and set a fixed value to it. When trying to save a different value it goes back to the fixed value:

add_filter( 'get_post_metadata', function( $value, $object_id, $meta_key, $single )
{
    if( '_download_limit' == $meta_key )
        $value = 100;

    return $value;
}, 10, 4 );

^{See Where to put my code: plugin or functions.php?}