It is proper Netiquette to save electronic receipts. Don't delete receipts.
Proof of purchase is the actual transaction receipt. Product descriptions are considered supplemental proof of purchase. They contain the information necessary to settle a dispute.
For example, items arrives damaged, different, and or not at all. Many banks request a description and receipt to process the dispute. Disputes can be made with the credit card issuing bank.
Electronic receipts are often printed and saved. Product descriptions should be included with receipts. Alternatively, the information can be save in an electronic format. Consumers generally keep a copy on their local machine. A backup cloud copy is also saved.
Product description of items purchased are saved for various reasons. Having an item description on hand lets you know exactly what you ordered. This is necessary because many sites change products frequently and it may not have an accurate description of the product you ordered because it is no longer carried, out of date, or out of stock.
Print and save receipts with a product description because they are proof of purchase for disputes.