com.apple.developer.storekit.external-purchase-link
A Boolean value that indicates whether your app can include a link that directs people to a website to make an external purchase.
Discussion
The com.apple.developer.storekit.external-purchase-link entitlement enables qualifying apps to include a link that directs people using the app to a website to make an external purchase. For more information, see External Purchase.
If your account receives this entitlement, which is also known as the StoreKit External Purchase Link entitlement, you can add it to your app by opening the project’s .entitlements file in Xcode. Then add the following key and set the corresponding value to true:
<plist>
<dict>
<key>com.apple.developer.storekit.external-purchase-link</key>
<true/>
</dict>
</plist>