A product I was working on was originally supplied in a vial of water. After about a year it was mush.
So I reworked the entire process with a new molding process, lyophilization and foil barrier pouch. We get a 4 year expiration date on it.
Yes, you have to have the aluminized film because it is an absolute barrier to moisture.
I packaging engineering we had to calculate the amount of time a carbonated beverage would last in a plastic bottle before going flat. It was only a few months. In a can it lasts years.
Well, you really ARE a packaging guy!