Here's a compact, practical checklist of features and capabilities to look for when evaluating a subscription management platform — grouped by function and including why each matters and what to ask vendors.

Core billing & pricing

• Flexible pricing models: support for recurring (monthly/annual), usage-based, tiered, per-seat, one-time, metered, and hybrid plans.
  Why: Your business may use multiple models now or later.
• Plan and product catalog management: easy creation/versioning of plans, add‑ons, coupons, and discounts.
• Proration and billing lifecycle rules: automatic proration for upgrades/downgrades, billing alignment, trial-to-paid transitions.
• Multiple billing cycles & billing day control: support custom cycles and invoice scheduling.

Invoicing, payments & revenue

• Multiple payment methods & gateways: card, ACH, wire, PayPal, Apple/Google Pay, and regional methods.
• Smart payment retry / dunning: configurable retry logic, email templates, recovery workflows, and automatic card updater support.
• Tax calculation & compliance: integration with tax engines (Avalara/TaxJar) or built‑in tax rules, VAT/GST handling, tax-inclusive/exclusive pricing.
• Invoicing features: customizable invoices, PDF generation, automated delivery, credit notes/refunds, and pro forma invoices.
• Multi-currency & localized billing: currency conversion, localized invoice language and formatting.

Subscriptions lifecycle & customer experience

• Self-service portals: customers can update payment methods, view invoices, change plans, cancel/reactivate subscriptions.
• Trials, holds & suspensions: configurable free trials, grace periods, holds, and pause/resume functionality.
• Account hierarchy & seats management: support for multi‑seat/enterprise accounts and seat provisioning.
• Notifications & communications: templated transactional emails (billing, dunning, receipts) and webhook/event hooks.

Revenue recognition & finance controls

• Revenue recognition automation: ASC 606 / IFRS 15 compliant schedules and deferred revenue reporting.
• Accounting integrations: native or near‑real‑time sync to QuickBooks, Xero, NetSuite, or ERP systems.
• Reporting & audit trails: changelogs, exportable transaction history, invoice lifecycle tracking.

Analytics, reporting & churn management

• Built‑in dashboards: MRR/ARR, churn (logo and revenue), LTV, CAC payback, cohort analysis, upgrades/downgrades.
• Custom reports & data exports: ability to export raw data or schedule reports.
• Experimentation support: A/B tests for pricing or packaging and cohort comparison.
• Customer segmentation: filter customers by plan, behavior, tenure, payment status.

Integrations & extensibility

• Robust API & SDKs: REST/GraphQL API, client libraries, webhook reliability, sandbox/test mode.
• Prebuilt integrations: CRM (Salesforce, HubSpot), ticketing (Zendesk), analytics (GA/BI tools), tax engines, payment gateways.
• Marketplace / app ecosystem: ready connectors to common tools to reduce custom work.

Security, compliance & reliability

• PCI DSS compliance & tokenization: ensure card data is handled securely (or vendor can scope it out).
• Data residency & encryption: at‑rest and in‑transit encryption; options for regional data storage if needed.
• Authentication & access control: SSO (SAML, OIDC), RBAC for admins, audit logs.
• Backups, uptime SLA & disaster recovery: documented SLA and incident history.

Operational & scaling considerations

• Scalability & performance: can handle your expected transaction volumes and seasonal spikes.
• Multi-tenant & segmentation support: for MSPs or platforms managing many customers.
• Migration & import tools: CSV/ETL support, guided onboarding, mapping for historical invoices/subscriptions.
• Admin UX: bulk operations (mass upgrades/cancellations), search, filtering, and change rollback.

Legal, localisation & governance

• Compliance with local laws: data protection (GDPR), local invoicing/tax rules, e‑invoicing where required.
• Terms versioning & consent capture: track acceptance of T&Cs and privacy policies per customer.

Support, pricing & vendor health

• Support & onboarding: dedicated onboarding, developer support, SLAs for support, success managers for larger customers.
• Transparent pricing: clear fees per transaction, per customer, or per feature; watch for add‑ons (tax, gateways, advanced reports).
• Vendor stability & roadmap: company maturity, funding/customers, product roadmap and release cadence.

UX & competitive differentiators

• Low-friction checkout & extensible hosted pages: customizable hosted checkout or embeddable components.
• Developer experience: good docs, examples, Postman collections, test fixtures.
• Feature flags & staged rollouts: deploy pricing changes safely.

How to prioritize for your business (short guide)

• Must-have (day 1): reliable payments, basic subscription types, invoicing, PCI scope reduction, basic reports, API, dunning, and tax handling for your region.
• Important (first 3–6 months): accounting integrations, revenue recognition, customer self-service, advanced billing models (usage/metered).
• Nice-to-have (later): experimentation, native marketplace integrations, advanced analytics, enterprise SSO and SLAs.

Questions to ask vendors

• How do you handle proration and billing alignment? Show an example.
• Do you support my pricing models (usage-based, seat-based, tiered)?
• Which payment gateways and tax engines do you integrate with out of the box?
• How do you automate revenue recognition? Can you export schedules to my ERP?
• What SLAs, uptime history, and incident reports can you provide?
• How is card data handled (tokenization), and are you PCI compliant?
• Can you migrate our historical subscriptions and invoices? What’s the effort/cost?
• What are the total costs (platform fees, transaction fees, add‑ons)?

KPIs to measure after implementation

• Time to first billing for new customers, failed payment rate, dunning recovery rate, MRR/ARR growth, churn rate (by cohort), average revenue per user (ARPU), days to reconcile/close.

If you want, tell me your business model (SaaS, media, hardware+service, B2C/B2B, expected transaction volume) and I’ll map these priorities to a short recommended feature checklist and red flags to watch for.