You can resolve this issue by Restoring your Purchase on your device.
Here's how to do so on Google Play:
1. Log in to your Headspace account
2. Scroll down to the "Get Headspace Plus" button on the Home Screen
3. Tap "Get Headspace Plus"
4. Tap "Restore Purchase" once the Buy Screen appears
Here is how to do so on your iOS device:
1. Log in to your Headspace account
2. Scroll down to the "Get Headspace Plus" button on the Home Screen
3. Tap "Get Headspace Plus"
4. Tap "Restore Purchase" once the Buy Screen appears
If you are still running into trouble, please send an email to: help@headspace.com.