The edX app does not yet support payment options for upgrading to the verified track for a course or program. To upgrade to the verified track for a course or program, sign in to edx.org and complete the payment on the website.
In the edX app, the course, or courses in your program, are listed in My Courses.
Note: Courses for which you can earn verified certificates often require exams such as timed or proctored exams. While you can complete most of the course using the edX app, you cannot take these types of special exams using the app.