How to request access token from leaflet to integrate with go js

Question

I am using GO JS with leaflet to show open street map and its working as expected with angular . Right now I am using access token given by them like

this.myLeafletMap = L.map("map", {}).setView(defaultOrigin, defaultZoom);

L.tileLayer("https://api.mapbox.com/styles/v1/{id}/tiles/{z}/{x}/{y}?access_token={accessToken}", {
  attribution: '© Mapbox © OpenStreetMap',
  maxZoom: 18,
  minZoom: 2,
  tileSize: 512,
  zoomOffset: -1,
  id: "mapbox/streets-v11",
  accessToken: "pk.eyJ1IjoiZ29qcyIsImEiOiJjaXppcnNkbDgwMzQ3MnFsNDFnY2phb2QwIn0.7AuVKrWdxQnJxa_W7qC3-w"
}).addTo(this.myLeafletMap);

, so i read somewhere this access token will get expire is it something like this or how I can regenerate new one if I want to use it for lifetime. and if its free library then why we need that token .Can somebody help me .

If I have GOJS licence what procedure I have to follow.