How-to guide
How to Combine Ads With a Subscription in LangChain
This guide shows how to combine ads with a subscription in a LangChain app, the goal being to run ads on the free tier and a paid ad-free tier together. It builds on the Monetzly server SDK, so the approach is specific to how LangChain produces and streams responses.
Overview
Ads and subscriptions are not mutually exclusive for a LangChain app. A common setup runs Monetzly ads on the free tier and offers a paid, ad-free tier for power users — capturing revenue from casual and committed users alike.
Implementation is a branch on the response path: enable injection for free-tier sessions and skip it for paying users, based on your own LangChain app's user state.
LangChain apps are usually built for RAG chatbots, tool-using agents, multi-step reasoning pipelines, and document QA, so combine ads with a subscription typically comes up while a user is mid-conversation, the moment where monetization has to be additive rather than disruptive.
How this works on LangChain
Grounded in this repo (src/app/api/agents/chat/route.ts) and the SDK's own LangChain example. A LangChain.js chat model returns a stream of message chunks that already carry a `content` field, so it can be passed straight into sdk.inject() with no adapter.
Because Monetzly's inject() accepts any async token stream, the LangChain side of this task is just mapping your output to it, no rewrite of your LangChain model call.
Steps
- Determine the user's tier from your LangChain app's auth/session state.
- Run ad injection for free-tier sessions.
- Skip injection (return the plain stream) for paying, ad-free users.
Frequently asked questions
Start monetizing in about 5 minutes
Wrap your existing LLM response stream with the Monetzly SDK and earn on every session, no paywall required.