To answer this question, the first thing you should look for is the date on your tortilla package. It will likely be a "sell by" date, which is the date by which the store should have sold the product, not when you need to use it by. You should use the tortillas before 7 days after the sell by date if you keep them on your counter or in the pantry. If you keep them in the refrigerator, you can get a month or more after the sell by date. If the date on the package is a "use by" date, then you should use the tortillas on or before that day. Always look the tortillas over before you use them to make sure there is no unusual discoloration or mold growing on them. If you see any spots of mold, no matter how small, discard the entire package without opening it. If you open the bag, mold spores may disperse into the air and land on other food you may have on the counter.