I would think if they arrived still fully frozen, packed well in freezer grade plastic, are kept in a good freezer and the packages closed up in between feeding day that 9 to 12 months is a good estimate. Give the supplier a quick phone call or an email to see what they say about this or also check their website. They may well have some sort of FAQ about this sort of thing.
I just ordered from them not too long ago, great quality except the first batch arrived and had thawed, dry ice was completely gone. They replaced it though at no cost. Check the following link under inquiries. http://www.ball-pythons.net/forums/s...ad.php?t=32829
0.0.1 Ball Python (Austin)
0.0.1 Albino California King
0.0.1 Corn Snake (Cornsuela)
0.1.0 Doberman/Shepherd/Lab mix (Zora)
"Q: How long will the frozen feeder animals last in the freezer?
A: Depending on how they are stored, most frozen feeder animals can last up to a year. It is a good idea to minimize any exposure to air by ensuring they are in air tight freezer bags. While we recommend not storing hairless feeder animals for more than 3 or 4 months, if properly sealed containers are used and air exposure is kept to a minimum, they can be kept for much longer."