This problem can sometimes occur from payments made through your Apple ID when you pay directly in your app on your Apple device.
What you need to do is to log back on to your account and press Restore iTunes subscription found towards the bottom in Profile tab > Choose Your Subscription if the active subscription isn't automatically found.
Below we have added a step by step guide for you to follow, to restore your iTunes purchase:
1. Log into your Natural Cycles account
2. Go to your Profile
3. Tap on ‘Choose/Change Subscription’ > Select the subscription you have purchased ( you will not be charged twice)
4. You will then end up on a screen/page similar to the one displayed below.
5. Once you see this page, please select 'Restore iTunes subscription' at the bottom of your screen.
If this doesn't work, delete your app and re-do the process.
It may be that you also could end up on the following page, as you may not have completed the registration of your Natural Cycles account. If this may be the case, then you can select 'Restore iTunes subscription' at the bottom of your screen and follow the steps that are provided.