If you subscribed via the AppStore
To obtain the invoice for your half-yearly subscription paid via the AppStore, simply consult the purchase history of your AppStore account
You can consult Apple's informations on https://support.apple.com/en-euro/HT204088
If you subscribed via Google Play
Click on a line to open the details and access the "download tax receipt" link.
NB: this link appears during the month following the payment.
If you subscribed via our website
To receive an invoice for your monthly, annual or lifetime subscription, all you have to do is send us your request by e-mail to firstname.lastname@example.org
Indicate your billing (postal) address and we will send it back to you by email once it has been issued.