If you purchased your subscription via our website, you will receive an email from us with the invoice attached.
If you purchased your subscription via Apple (e.g. with an iPhone), you can go to the website https://reportaproblem.apple.com/ and download your invoice there.
If you purchased your subscription via Google (e.g. with an Android smartphone), you can download your invoice using this help page https://support.google.com/store/answer/13714320?hl=en.