Today I bought a 2 oz (56.7 grams) bottle of Bay Leaves. The "best use by" date is 01/2015. I've read that spices and herbs go "off" after a year or so, depending. Can I believe the 2015 date on these bay leaves?
The use-by dates on all spices are mainly hokum. Most spices last for six months in whole form, herbs can be dried and last about three, after that time the taste is going to weaken and change as essential oils leave the spice. If you keep your spices in an airtight dark container you can eek out a little more time, but I would highly recommend that if you want fresh spices you grind yourself and keep fresh herbs on hand (it's very little work to grow your own).
That said, bay leaves last me quite a while, and even after I know they should be retired I tend to just throw more of them in the pot to achieve the same effect.
Bay leaves lose potency if stored at room temperature. They will last much longer if stored in the freezer. This is based on a Cook's Illustrated magazine article. They did a taste test a few years ago, and were amazed at the flavor difference after 6 months (between frozen and non-frozen bay leaves).