For subscriptions paid via web app
Go to the Billing tab in the web platform
(click on credit card icon in left hand menu - see image below)Select the farm you want to view invoices for
You can download a PDF of invoices for each month you have been billed
In-App Purchase - iOS
If you are currently paying for your subscription via Apple App Store payments, you can access your invoices through your Apple devices.
iPhone
Go to Settings and select your Apple ID.
Select Media & Purchases and then View Account.
Scroll down and tap Purchase History.
Tap on fieldmargin to view subscription details.
You can screenshot the payment information or tap Resend to be emailed them.
Mac
Click Account > View My Account from the menu bar.
On the Account Information screen, scroll down to Purchase History.
To the right of Most Recent Purchase, click See All.
Click the Order ID to the right of the subscription. For apps, you can click More to view all details.
Capture a screenshot of the receipt or use the Resend option to receive the subscription receipt via email.
In-App Purchase - Android
If you are currently paying for your subscription via Google Play Store payments, you can access your invoices through your Android devices.
This article from Google explains how you can get receipts from the Play Store: https://support.google.com/store/answer/13714320?hl=en-GB