Describe access as a business rule
A subscription integration is easy to underestimate when the brief says only that the two sites should share a login. Registration, payment, cancellation and content access are different events. Each needs an agreed outcome, including what a visitor sees while an update is delayed.
Start with a simple responsibility table. Identify the system that owns the customer record, the system that decides subscription status, the system that serves restricted content and the place where support investigates a mismatch. Avoid letting both applications independently decide the same entitlement.
Separate identity from entitlement
A person being signed in does not necessarily mean they have paid access. Model those decisions separately in the brief and acceptance checks. For example, a registered visitor may have a valid account while remaining limited to free content; a payment event may change entitlement without creating a second identity.
Our Laravel–WordPress case study describes Laravel as the source of truth, with a custom WordPress integration handling user events, roles and session behavior. Its operational observations belong to that historical implementation. They are not a promise that a new integration will have the same results or recovery needs.
Design the failure path before launch
Ask what happens if one system accepts an update while the other is unavailable. Support should be able to identify the affected account and reconcile it without guessing which application is correct. Record an event identifier, the intended change and its outcome using a retention policy appropriate to the project.
Test repeat delivery as well as first delivery. A repeated notification should not create another customer or grant an unrelated entitlement. Then test cancellation, failed payment and recovery with the same care as signup. These cases expose assumptions that a successful demonstration often misses.
Choose authentication for the actual boundary
WordPress documents cookie authentication for requests within a logged-in WordPress context, and Application Passwords for suitable external API access over HTTPS. Those mechanisms do not automatically provide cross-application customer sign-in. The integration's authentication and authorization design must match its users and trust boundaries.
A useful scope therefore includes an event map, access rules, credential ownership, failure handling, support instructions and acceptance scenarios. Bring the existing billing and account flows into the discovery conversation. Connecting endpoints is one part of the work; making access understandable to customers and support is the outcome.
Further reading
Laravel–WordPress subscription integration
WordPress: REST API authentication — checked 18 October 2026.