Edit in JSFiddle

//as container you can use as textarea, so and div
tinymce.init({
  selector: '#editor',
  height: 300,
  //don't forget to install 'BeyondGrammar' as a plugin and part of toolbar
  plugins: ["paste", "BeyondGrammar", 'link'],
  toolbar: [
    "undo redo | styleselect | bold italic link | alignleft aligncenter alignright alignjustify | bullist numlist outdent indent | BeyondGrammar"
  ],

  //all options placed in `bgOptions` object
  bgOptions: {
    service: {

      //localization for BeyondGrammar interface, will be used default or got by system information, please use same version with the plugin.
      i18n: {
        en: "https://prowriting.azureedge.net/beyondgrammar-tinymce/1.0.16/dist/i18n-en.js"
      },

      //You should signup for getting this key
      apiKey: "E8FEF7AE-3F36-4EAF-A451-456D05E6F2A3",

      //[optional] You can specify it for permanent access to your settings and dictionaries
      //userId: "<YOUR_USER_ID>",

      //[optional] path to js file with BeyondGrammar Core
      //sourcePath : "", 

      //[optional] path to service which provides grammar checking
      // url shouldn's contains / in the end
      //serviceUrl : "https://rtg.prowritingaid.com/api/v1", 
    },
    grammar: {
      //[optional] Default language [en-US, en-GB],
      languageIsoCode: "en-US",

      //[optional] checking Style. By default is "true"
      checkStyle: true,

      //[optional] checking Spelling. By default is "true"
      checkSpelling: true,

      //[optional] checking Grammar. By default is "true"
      checkGrammar: true,

      //[optional] Show thesaurus information by double click, by default true
      showThesaurusByDoubleClick: true,

      //[optional] Showing context thesaurus, works only if showThesaurusByDoubleClick = true, by default false
      showContextThesaurus: false,
    }
  }
});

<!-- Include tinymce and RTG code sources -->
<script src="https://cdn.tinymce.com/4/tinymce.js"></script>
<script src="https://prowriting.azureedge.net/beyondgrammar-tinymce/1.0.58/dist/beyond-grammar-plugin.js"></script>

<div id="editor">
  <p>
    Novalk Djokovic is set to miss the US Open after one of his doctors made an announcement that he will need six to twelve weeks to recovers from a elbow injury.
  </p>

  <p>
    But Andy Murrey's chances of playing at Flushing Meadows would appear more positive, with the Scot continuing his rehabilitation from a hip problem.
  </p>

  <p>
    The last grandslam of the year starts in just under five weeks on August 28, meaning Djokovic will run out of time if the latest assessment is correct.
  </p>

  <p>
    <b>Injured Djokovic starting to consider a break away from tennis</b>
    <br />The 12-time major champion was forced to retire injured during his Wimbeldon quarter-final against Tomas Berdych earlier this month and said after the match that he had been feeling pain in his right elbow for over a year and a half. According to
    his physio its not doing very well. If he does return he will be more likely to injure it again.
  </p>

  <p>
    He has since been seeking advice from specialists, including Serbian doctor Zdenko Milinkovic, who said Djokovic is suffering from a "bruised bone due to excessive playing".
  </p>

  <p>"Nole must rest for six to 12 weeks," Milinkovic told Sportski Zurnal, a sports newspaper in Serbia.</p>

  <p>
    The next examination will know wether this asdsessment stays or changes. During this period, he is not going to train with a racket but he will run other sessions, such as fitness and the like.
  </p>
</div>