Do plant root cleaning enzymes expire?

[Glassdub]

Such as Dyna-Gro Zyme, I thought I read somewhere that they do not but I can't presently confirm.

 

[Glassdub]

s
I wrote the company, I'm expecting a stock answer of 2 years best, but they have a vested interest in selling smaller amounts (in the case of this) at close to double the price, I prefer to buy by the gal on most of their line but I may go a qt on this as I'm having a hard time confirming.

 

[Glassdub]

"Our Zyme product doesn’t have a specific expiration date. Its effectiveness will last around 2-3 years. Storing it in a cool environment, out of direct sunlight, will extend its shelf life.

Happy Growing!
Susan Sommer
Dyna-Gro
Richmond, CA
(800) 396-2476"

About as suspected.