[Vuejs]-Changing value in JavaScript code/tag with Vue.js

You need to add ld to your app data and update it on response from axios:

data: {
    message: [],
    ld: 0, // default id you want to start it from
},
methods: {
    loadmore: function () {
        axios.get('http://127.0.0.1:5000/api/products/'+this.ld)
             .then(response => {
                 const messages = ...response.data;
                 this.message.push(messages);
                 this.ld = messages.pop().id;
             });

    }
}