You may wish to submit your Academia Premium purchase to your department or institution to have it reimbursed, or simply wish to have a receipt to keep track of your expenses. To do so, head to your Academia Premium settings. You can do so by clicking your name in the top right-hand corner, then click "Account settings."
Then, select "Premium Subscription."
Simply click the small triangle next to the year you wish to get your receipt for.
Then, click "View Receipt" for the payment during that year you wish to save. You'll view and automatically download your receipt.
If you need a payment invoice that includes additional information, such as VAT information, billing address, or other relevant details, you can always add it! Select "Add Billing Details."
Then enter your billing information in the relevant fields.
When you've added all the information, select "Submit." Then, click "View Receipt" again, and your new receipt should have your billing information!