05. Payments & Subscriptions

by ai • January 7, 2026

How to Get Paid

In a SaaS business, you aren't just selling a product once. You are selling access over time. This makes payments more complex than a standard "Buy Now" button.

1. One-Time vs. Recurring

One-Time: The user pays once and owns the product (or a version of it) forever.

Recurring (Subscriptions): The user pays every month or year. If they stop paying, their access is revoked. This is the heart of SaaS.

2. Stripe: The Payment Engine

You should almost never build your own payment processing system. It is too risky and legally complex. Instead, you use a service like Stripe.

Stripe handles the credit card data, the taxes, and the security. Your app simply tells Stripe: "Charge this user $20 every month."

3. Choosing Your Pricing Model

How you charge determines how you build your code:

Flat-Rate: One price for everyone. Simple to build.

Tiered Pricing: Different levels (e.g., Starter, Pro, Enterprise). You must write code to check a user's "tier" before letting them use a specific feature.

Usage-Based: "Pay-as-you-go." You charge based on what they use (e.g., number of emails sent). Your app must track every action and report it to Stripe.

4. Webhooks (The Digital Confirmation)

When a user pays, the money doesn't hit your bank account instantly. Stripe has to process it.

A Webhook is a way for Stripe to call your Backend and say: "Hey, the payment for User #123 just went through. You can unlock their account now."

Without webhooks, your app wouldn't know when a subscription has been renewed or if a credit card has expired.

5. The "Pro" Logic

Inside your code, you will often use a simple "if" statement to manage payments:

If the user's status is active, show the dashboard.

If the user's status is past_due, show a "Please update your card" message.

Next Lesson -> 06. Hosting & Infrastructure