A reader sent me this question looking for advice.  What do you recommend?

In the late 90's in moved and packed a lot of things away at my mother's barn and wanted to get them only to be told that my brother had thrown all of my boxes away.  last week my mother called to tell me that she actually found them further back in the barn and if iwanted a box that had a ton of cookbooks in them.  ( a weakness for cookbooks used to be a downfall) anyway, as i was looking through them i saw several books had coupons in the back of them that state "NO EXPIRATION DATE".  (GASP) imagine my surprise and glee.  BUT, now i am not sure what to do.  these books are from the late 80's and early 90's, so should i use them because there is not an expiration date or just keep them as a novelty?  just a curious question, i can't wait to read what you think.  thanks!!!!!!!!!!!!!