When do Elmish subs get disposed, if at all?

From the Elmish docs:

open Elmish
open Fable.Core

let timer initial =
    let sub dispatch =
        JS.setInterval
            (fun _ ->
                dispatch (Tick DateTime.Now)
            )
            1000
            |> ignore
    Cmd.ofSub sub

Program.mkSimple init update (fun model _ -> printf "%A\n" model)
|> Program.withSubscription timer
|> Program.run

If this were part of a more complex app, it would be good for the setInterval to be cancelled if the component is unmounted.

With React hooks, this is part of the component life-cycle.

I am wondering how this works in Elmish?