I’ve searched to see if this has already been answered but could only find information on the 3 day expiration. I have a group member trying to find out if it’s okay to use her old pods that say December 2018 on them. My guess is it’s fine, but I also thought you guys were fine and see?
Joking… 
Yes. They can be used. I’ve used them as much as 6-months expired and they’re fine and I believe others have done the same or even farther back.
Perfect. Thank you, sir. 
December isn’t that old, but I wouldn’t want to stretch it too long because …
Not sure if anyone has determined how old is too old.
@Eric, plz share your wisdom here. I’ve used expired ones fine but not sure how far back is safe given your comments on Battey life.
Thank you, @Beacher. There were others who responded to her about batteries dying. I had no idea.
I used expired pods, too, not realizing it. These pods had a high failure rate, something like 40% of the box failed. I called Insulet and they confirmed that expired pods shouldn’t be used due to the high failure rate.
I have not kept any for a long time just for the sake of seeing if it would work, because I only started using them 2 1/2 years ago. 
I can tuck a few pods away, and then come back and revisit this subject in a few years after using them.
I used a whole box of pods that were 6 months expired and not a single one of them errored out. I guess I got really fortunate!
I just had three Day 1 pod failures (within first 24 hours) in a row. My pods were 26-28 days expired. I have now chucked the last eight pods with that expiration date because I’m tired of wasting insulin since I purposefully don’t recover the insulin out of the pods.
Why purposefully ?
If they fail right away, I’ll recover it. If I’ve been working outside (hot), showered (heat exposure), swimming, etc with it on and had the pod on for close to a day or more, I let it go. I just try to limit my variables for the next pod/insulin load.
Well, one more thing to keep track of. I totally didn’t think about the pods expiring. I feel like we go through them – and we don’t have a lot of spares. But this was helpful! I’m sorry that you had to find out the hard way, but it is good to know.