How to get an invoice (VAT invoice) for your purchase?

Purchases on learn.supermemo.com
When placing your order, tick the box next to “I want to receive an invoice for my company” and fill in the required details. You’ll find your invoice later (no later than the 15th day of the following month) under “More” > “Order history”.

Purchases on Google Play
You can find instructions on how to obtain a company invoice here: https://support.google.com/googlepay/answer/7644144?hl=en 
Purchases in the App Store
You can find instructions on how to obtain a company invoice here: https://www.apple.com/shop/help/payments