Publishers must use ld+json structured markup on each of their article pages. When the pages are crawled and indexed, this markup is used by Google to understand which content should be associated with which product, and subsequently used to populate the “From your subscriptions” carousel and other reader-facing surfaces.
<script type="application/ld+json">
{
"@context": "http://schema.org",
"@type": "NewsArticle",
"isAccessibleForFree": false,
"publisher": {
"@type": "Organization",
"name": "Herald Foo Times"
},
"isPartOf": {
"@type": ["CreativeWork", "Product"],
"name" : "Herald Foo Times",
"productID": "herald-foo-times.com:basic"
}
}
</script>
For more information on the complete spec for entitlements, please see the SwG devsite article on structured data markup.