Design the event instrumentation for Premium at scale

Problem Statement Description

Product context: Spotify is an audio streaming company; its products include music, podcasts, audiobooks, playlists, recommendations, creator tools, subscriptions, and ads.

Spotify Premium spans acquisition, trial eligibility, subscription purchase, entitlement changes, listening experience, retention, and churn across mobile, desktop, web, connected devices, and backend billing systems. In this technical PM interview, you are asked to design the event instrumentation needed to understand and operate Premium at global scale.

Assume multiple teams depend on this instrumentation: growth teams measuring conversion, payments teams monitoring purchase and renewal flows, personalization teams understanding Premium behavior, finance teams reconciling subscriptions, and advertising teams understanding how Premium adoption affects ad-supported inventory and monetization. The challenge is to define an event system that is useful, reliable, privacy-conscious, and consistent across platforms without over-instrumenting the product.

You should focus on what needs to be captured, how data should flow from clients and services, how quality and trust are maintained, and how the instrumentation supports product decisions. Do not design the Premium product itself; design the measurement and event foundation that allows Spotify to evaluate and operate Premium effectively.

The experience should consider:

- Core Premium user journeys to instrument, such as plan discovery, trial start, checkout, payment success or failure, entitlement activation, upgrades, downgrades, cancellations, renewals, and reactivation.

- Event taxonomy, naming conventions, required properties, identifiers, timestamps, and how events connect across anonymous, logged-in, household, and subscription-plan states.

- Client-side versus server-side instrumentation responsibilities across iOS, Android, web, desktop, connected devices, billing systems, and entitlement services.

- Data reliability requirements, including deduplication, ordering, retries, schema validation, backfills, late-arriving events, and cross-platform consistency.

- Privacy, consent, security, and regional compliance considerations, especially for payment-related metadata, minors, household plans, and advertising-related use cases.

- Observability and operational tooling for detecting broken events, volume anomalies, funnel drops, SDK regressions, and downstream pipeline failures.

- Rollout strategy for introducing or changing instrumentation without disrupting existing dashboards, experiments, financial reporting, or advertiser-facing analytics.

- Product trade-offs between measurement depth, app performance, engineering complexity, user trust, and long-term maintainability.

Your goal is to present a clear technical product plan for Premium event instrumentation that enables trustworthy analytics, experimentation, operational monitoring, and strategic decision-making at Spotify scale.