After you marked as complete 100% of the lectures in your course, including "marking as complete" the course evaluation, you can access your certificate of completion.
Once you mark 100% of the lectures as complete, your course certificate will appear. Under your course certificate is a "Download" button, press this button and you can download your course certificate and save it to your computer, and print it if you wish.
If you need to access your course certificate again after you exit out of the course. Just log back into your teachable account, click on the desired course, go to course curriculum in the sidebar, click on the Evaluation (note. You do not need to fill it out again) Simply press complete and continue again and your course certificate will automatically pop up for you.