app.component.html

<StackLayout>
    <Label [text]="appVersion"></Label>
</StackLayout>

app.component.ts

import {Component, OnInit} from "@angular/core";
let appversion = require("nativescript-appversion");

@Component({
    selector: "my-app",
    templateUrl: "app.component.html",
})
export class AppComponent implements OnInit {

    appVersion: string;

    constructor() {
    }

    public ngOnInit() {
        appversion.getVersionName().then((v) => {
            console.log("Your app's version is: " + v);
            this.appVersion = v;
        });

    }
}

console.log

JS: Your app's version is: 1.0