How I Added In-App Subscriptions in 30 Minutes Using Revenue Cat + AI

Plus prompts I used in Claude Code

I’ve been doing mobile apps for over 15 years and handling payments inside mobile apps is very painful. It’s alot of work to handle all the product IDs, entitlements, groups, etc. It’s extra painful if you’re dealing with subscriptions.

You’ve got to handle upgrades, cancellations, paywalls, different pricing tiers, testing sandbox accounts, App Store metadata, product IDs that need to match perfectly across three different dashboards... and if ONE thing is off? Nothing works. You get vague errors. You question your life choices.

But here’s the good news: I figured out how to do this in about 30 minutes using Revenue Cat and AI coding agents (Claude Code, Cursor, ChatGPT—whatever you’re using).

And today, I’m walking you through the exact process so you can skip the frustration.

What We’re Building

I’ll show you how I add the following into my live Mac app:

• Working in-app subscriptions (monthly + annual plans)

• A professional paywall

• Revenue Cat handling all the billing complexity

• Everything tested and ready to ship

No PhD in App Store bureaucracy required.

The 3-Part Setup (Here’s the Roadmap)

Before we dive in, here’s what we’re doing:

1. Revenue Cat Setup → Configure your products, offerings, and entitlements

2. App Store Connect → Set up API keys and subscription metadata (this is the annoying part)

3. SDK Implementation → Let AI do the heavy lifting with your coding agent

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• Claude Sonnet 4.5 is out and I tested it, it’s the best coding LLM right now.

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Part 1: Setting Up Revenue Cat

Step 1: Sign up at RevenueCat.com (it’s free up to USD$2.5K)

Step 2: Choose your platform (I’m doing Mac/iOS, so I clicked “Apple Platforms”)

Step 3: You’ll see you need to set up your App Store Connect API configuration

Don’t panic. Here’s what to do:

Getting Your App Store Connect API Key

• Go to App Store Connect

• Navigate to: Users and Access → Integrations → Team Keys

• Click Generate API Key

• Give it a name (something like “Revenue Cat Integration”)

• Set access to App Manager

• Download the .p8 file

• Copy your Issuer ID (you’ll need this)

Step 4: Back in Revenue Cat, upload that .p8 file and paste your Issuer ID

Boom. You’re connected.

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Part 2: The App Store Metadata Dance 💃

Here’s where it gets tricky—and where most tutorials leave you hanging.

Setting Up Subscriptions in App Store Connect

1. In App Store Connect, go to your app

2. Click In-App Purchases → Subscription Groups

3. Create a new group (I called mine “Pro”)

4. Add your subscriptions (Monthly + Annual)

CRITICAL: The product IDs MUST match exactly with Revenue Cat. I mean character-for-character identical. If they don’t match, nothing will work and you’ll get zero helpful error messages.

Here’s what I did:

• Monthly: Product ID = monthly (same in Revenue Cat)

• Annual: Product ID = annual (same in Revenue Cat)

The Secret They Don’t Tell You

Even if App Store Connect says “Missing Metadata,” you STILL need to fill out:

• ✅ Availability (which countries)

• ✅ Pricing (set your tiers)

• ✅ Localizations (at least English)

• ✅ Subscription display name

• ✅ Description

• ✅ Review information (yes, even screenshots)

I know it seems like busywork, but Revenue Cat can’t retrieve the data unless this is all filled in. Trust me on this one—I spent an hour debugging before I realized this was the issue.

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Part 3: Let AI Build Your Paywall

Okay, now for the fun part.

Implementing the Revenue Cat SDK

Revenue Cat has a brilliant feature: they give you AI-optimized prompts.

Here’s what I did:

1. In Revenue Cat dashboard, go to SDK Implementation

2. Click on your AI tool (I used Claude Code, but ChatGPT/Cursor work too)

3. Copy the context prompt they give you

4. Paste it into your AI coding agent with: “Implement Revenue Cat SDK”

Literally that simple. The AI knows exactly what to do.

Adding the API Key

You’ll need your Revenue Cat API key:

• Go to Revenue Cat → Settings → API Keys

• Copy your public SDK key

• Paste it into your code where the AI tells you

Building the Actual Paywall

Here’s the prompt I gave Claude Code:

I’m using Revenue Cat for subscription management. 

Revenue Cat ID: [your_id_here]
Annual Package ID: annual
Monthly Package ID: monthly

Annual price: USD $19.99
Monthly price: USD $9.99

Implement a paywall feature where the user can upgrade to Pro to unlock additional AI analysis features.

Hit enter. Watch the magic happen. ✨

Claude built me a complete paywall with:

• Both subscription options displayed

• Proper Revenue Cat integration

• Purchase flow handling

• Restore purchases button

• Error handling

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Testing It Out

Fire up your app, click your new “Upgrade to Pro” button, and... it works.

The paywall shows up. The prices are correct. You can test purchases using App Store sandbox accounts.

That’s it. You’re done.

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Key Takeaways (Copy These If You Want)

🔑 The product IDs MUST match between Revenue Cat and App Store Connect—this is the #1 gotcha

🔑 Fill out ALL the App Store metadata even if it says “missing metadata is okay”—Revenue Cat needs it to work

🔑 Use the AI prompts Revenue Cat provides—they’re specifically designed for this

🔑 Don’t try to manually code this—let AI handle the SDK implementation (seriously, why make your life harder?)

🔑 Set up both monthly AND annual—annual subscribers have way higher LTV

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What I Spent 3 Hours Debugging (So You Don’t Have To)

• Product ID mismatches → 1 hour lost

• Missing App Store metadata → 1 hour lost

• Forgetting to add the API key → 30 minutes lost

• Not setting up subscription groups properly → 30 minutes lost

Total time once I knew what I was doing: 30 minutes.

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Your Next Steps

1. Sign up for Revenue Cat

2. Follow the steps above

3. Let your AI coding agent do the implementation

4. Test with a sandbox account

5. Ship it

If you want to see the video walkthrough of this entire process, I recorded it step-by-step—reply to this email and I’ll send you the link.

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This Week’s AI Tools & Resources

I’ll keep this short since this post is already packed:

• Revenue Cat → Subscription infrastructure (what we just covered)

• Claude Code → My go-to for implementing SDKs and integrations

• App Store Connect API → Docs for the key setup we did

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Got questions? Hit reply and ask.

Seriously—if you get stuck on the metadata part or the product IDs aren’t matching, I’ve been there. I’ll help you debug.

Did this save you hours of frustration? Forward this to another developer who’s about to go down the subscription rabbit hole.

See you next week with another practical breakdown,

Keith

P.S. - If you’re building something with subscriptions and AI, I want to hear about it. What are you working on? Reply and tell me!

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