Some creators, selling limited-run digital products, set their download links to expire after a certain number of days or downloads.
Gumroad sends an automated receipt to the email address you used at checkout. gumroad download
Look for an email from "Gumroad" with the product name in the subject line. selling limited-run digital products
: For authors, Gumroad can "stamp" the buyer's email on every page of a PDF to discourage piracy. gumroad download
Avoid generic names like final_v2.pdf . Use Product_Name_Guide.pdf .