Yes. To purchase a course upgrade please:
1. Launch the Insight Timer App
2. Press on the 4th button the navigation bar named 'Courses'
3. Select the course you wish to purchase
4. Wait for the 'Begin' button to appear at the bottom of the screen
5. Select 'Begin' and choose 'use once'
6. Then start the course and press the '...' buttons at the top and choose 'Own for 15USD' (or the equivalent to your currency) to upgrade the course to multi-use.