PDF Download Adjustment

We have a new website under development which is 90% complete. We are a publisher and sell print and pdf copies of our reports and books from the site. As it now stands, an end user must register with the site and then when he orders, the pdf goes into a section on the site created specifically for the orderer. However, we want the person who orders to receive an email with a link that enables them to download the report for a limited time period, say 1 day, before the link becomes non operable. We want the person who orders to be able to do so without registering, and then we want the site to send a link to an email address as described above. The site is in PHP.