Netlify Login & Stripe Subscriptions

I run a single-page HTML/JavaScript web app on Netlify that organises lawn-bowls draws for our club. The next step is to add two connected features:

1. A secure email-and-password login that stores each subscriber’s credentials and applies user-specific permissions.

2. Stripe integration for recurring subscription payments so members can pay their annual fees directly through the site. The offering of a 30 day free trial period.

The codebase is small and already sits on a GitHub repo linked to Netlify, so I expect the new functionality to be delivered as a clean pull request with all necessary serverless functions, environment variables and front-end hooks clearly documented.

What I need:
1. A simple login/signup system so only paying users can access the app or a family share arrangement with say 3 shares
2. Stripe payment integration with an annual subscription following a 30-day free trial
3. A basic admin view so I can see who has paid and manually grant or revoke access if needed
4. The app itself should not change — just gate it behind the login

Tech I’m already using:

• Netlify (hosting)
• Plain HTML, CSS, JavaScript (no frameworks)
• No existing backend or database

What I’m looking for in a developer:

• Experience with Netlify Functions or a simple backend
• Experience with Stripe payments
• Able to explain what you’re doing in plain English
• Deliver the total application I can manage myself going forward

Questions I want answered in your proposal:

• What tech will you use for the login/authentication?
• How will you make sure someone can’t access the app without paying? Or pass on their logon details to others
• What ongoing costs should I expect beyond Stripe’s transaction fees?
• How long will it take?
Please keep the tech choices aligned with Netlify’s ecosystem (Functions, Identity, etc.) or propose an equally streamlined alternative that won’t require moving away from the current hosting setup.