Boxed chocolates can last longer than you may expect, if stored properly. StillTasty advises you to store chocolates at room temperature to get six to nine months out of them. (Even if they've been opened.)
Additionally, StillTasty writes that you can extend chocolate's life by cranking down the temperature. "As a general rule, refrigerating chocolate can extend its shelf life by at least 25%, while freezing can prolong it by 50% or more," the website says. "Place the original box in a heavy-duty plastic freezer bag, seal it tightly, and then refrigerate for up to one year, or freeze for up to 18 months for best quality. Thaw frozen chocolates in the refrigerator."
StillTasty mentions, however, that this is not the case for luxury, artisanal, handmade chocolates — at room temp, they will stay fresh for two to three weeks.