It says packed for sale in December 2014. It doesn't say use by. Not many people can plant in December. I would assume that the seed packers want you to plant them in 2015. These seeds will last easily 2-3 years and much longer if stored properly.
You bet! It's confusing the way that they are packaged. I had to do a lot if reading to figure it out. My mother kept seeds for years. She kept them dry and packaged in plastic and usually in the bottom of a dresser. Every time we moved, she planted a new flower garden..we moved almost every year. Good memories. Thanks for writing!