In the United States storefront, apps can include buttons, external links, and other calls to action for other ways to buy without an entitlement.
In other storefronts, linking out to buy digital goods needs an entitlement: the StoreKit External Purchase Link Entitlement or, where permitted, the Music Streaming Services Entitlement. Since Apple's October 16, 2026 update, the link goes to a "permitted destination" rather than a website you own or maintain, approved destinations can vary by region, and each entitlement is limited to specific storefronts and to certain platforms within them.
With an entitlement, the link can tell users where and how to buy, and that items may be cheaper there. Without one, outside the US, the app and its metadata can't include buttons, links, or calls to action that point to purchasing other than In-App Purchase.
Music streaming apps no longer have a separate bullet in the guidelines: the Music Streaming Services Entitlement now sits under the StoreKit External Purchase Link rules. Check your entitlement agreement for what your link may say.