Weekly Subscription & UI Enhancements

I already have a fully published app on both Android and iOS, built with a solid code-base that is running well in production. What I now need is an update that introduces a WEEKLY subscription using the native in-app purchase systems (Google Play Billing + Apple In-App Purchases) and a refresh of two core areas of the product experience.

Scope of work
• Payments ─ set up a recurring weekly plan. When a user is on this plan they should automatically unlock only the premium features I flag, while free users continue to see the current basic set. The subscription screen, purchase flow, receipt validation and graceful handling of expired or cancelled plans all have to be covered on both stores.
• Design & layout ─ modernise key screens so they look consistent across phone sizes, follow the latest platform guidelines and feel visually cohesive with the new paywall.
• Accounts & profiles ─ tidy up the profile section, add any necessary fields for the new premium tier, and make sure sign-in/up flows remain smooth after the payment changes.

Deliverables
– Updated Android and iOS builds ready for store submission
– Source code with clear comments around the payment module
– Test cases (unit or manual steps) proving purchase, renewal, cancellation and downgrade states
– Design assets and style guide for the refreshed screens

Acceptance criteria
1. A weekly subscription can be started, renewed, cancelled and restored on both platforms without errors.
2. Only the flagged premium features become available while an active subscription exists.
3. UI adjustments render correctly on common device sizes and pass App Store / Play Store review guidelines.
4. Existing free users can continue using the app exactly as before.

If you have recent experience integrating Apple/Google subscriptions and polishing UI at the same time, I’d love to see examples and discuss timelines.