Hello @AzharUddinSheikh,
If you have subscribed for one month and finish the course, you can get the certificate.
Make sure that you finish and mark every single lesson as completed. As suggested in the following forum post: The Ultimate HTML5 & CSS3 Series: Part 1 - Certificate. @SAM said,
Make sure you marked every single “lesson” (including “Getting Help”, “Follow Me Around”,…) completed. If it still doesn’t work, contact the team via your personal menu.