I purchase deals online all of the time. Deals from sites like Groupon, Living Social, etc. that you have to print, always have expiration dates. Usually they expire within 6 months to a year...and sometimes in even less time. It's hard to keep track of everything that I've printed and make sure that I use it before it expires.
I created a printable form to keep track of these deals. I have one version that's really basic that you can download for free here. I have also updated all of the other free printables that I have available for download (except the calendar) with matching fonts and color scheme. Check them out on the free printables page.
I have also created a more "advanced" log that you can purchase from my Etsy store. It comes in vertical or horizontal (your choice) and is set up by month. I am currently using the horizontal document (see picture at very bottom of my example that I'm using in my home management binder). This makes it easy to see what deals are expiring in the up coming months.