# Cancel Subscription (/sdks/elixir/how-to/events/cancel-subscription)



## Overview [#overview]

A live Events subscription holds a background process open indefinitely, so a long-running service needs an explicit way to tear one down without closing the whole client connection — for example when a feature flag disables a channel, a worker is draining before shutdown, or a subscription needs to be re-created with different options. Calling `KubeMQ.Subscription.cancel/1` stops delivery cleanly and releases those resources on both sides.

`KubeMQ.Client.subscribe_to_events/3` registers the callback and returns a subscription reference immediately, so the process keeps running in the background until you cancel it. `KubeMQ.Subscription.cancel/1` stops the subscription and releases server-side resources, and `KubeMQ.Subscription.active?/1` gives you a way to check the current state — useful for confirming a cancellation actually took effect before moving on.

**Gotchas:** cancelling one subscription doesn't affect others on the same channel. Events already in flight when you cancel may still be delivered briefly afterward. And because Events are fire-and-forget, anything published after cancellation is simply dropped for this subscriber — there's no queue to catch up from later.

## Prerequisites [#prerequisites]

* KubeMQ server running on `localhost:50000`
* Elixir SDK installed (`{:kubemq, "~> 1.0"}` in mix.exs)

## Code [#code]

```elixir title="main.exs"
channel = "elixir-events.cancel-subscription"
{:ok, client} = KubeMQ.Client.start_link(address: "localhost:50000", client_id: "elixir-events-cancel")

{:ok, sub} =
  KubeMQ.Client.subscribe_to_events(client, channel,
    on_event: fn event -> IO.puts("Got event: #{event.body}") end
  )

IO.puts("Subscription active? #{KubeMQ.Subscription.active?(sub)}")

:ok = KubeMQ.Client.send_event(client, KubeMQ.Event.new(channel: channel, body: "Before cancel"))
Process.sleep(500)

:ok = KubeMQ.Subscription.cancel(sub)
IO.puts("Subscription cancelled. Active? #{KubeMQ.Subscription.active?(sub)}")

:ok = KubeMQ.Client.send_event(client, KubeMQ.Event.new(channel: channel, body: "After cancel"))
Process.sleep(500)

IO.puts("Second event sent but no subscriber to receive it.")
KubeMQ.Client.close(client)
```

## How It Works [#how-it-works]

* `KubeMQ.Subscription.active?/1` checks whether a subscription is still receiving events
* `KubeMQ.Subscription.cancel/1` stops the subscription and releases server resources
* Events published after cancellation are not delivered to the cancelled subscriber

## Related [#related]

* [Basic Pub/Sub](/sdks/elixir/tutorials/basic-pubsub)
* [Graceful Shutdown](/sdks/elixir/how-to/error-handling/graceful-shutdown)