Indeed. You should keep it dark and cool. If it's properly sealed, preferably in the fridge. And even then it will go bad over time. It does differ between the different forms these testkits come in, the multi-use ones that come in a glass bottle with a screw cap will go bad faster than for instance the eztest single use ampules that are sealed until use and contain the reagent in gel form in stead of a regular liquid. I noticed in case of my multi-use testkit, it remained good to use for about 1 to 1,5 years in the fridge but went bad much, much faster at high temperatures and/or with sunlight. You can test if it's still good either by testing some drugs in your possession that you know to be good, or by using aspirin or sugar, which also should produce their own test result colors. Generally when the testkit is going bad, I noticed the reaction happens slower and the final color appears more dilute
