It says that on the part of the package that gets torn off when you open it, so once you open it it won't say that on the package anymore and you don't have to refrigerate it.
JK I refrigerate mine just in case the Stevia in the container may degrade.
This wal mart stevia is not sweet, taste some on your finger. The citric acid and vinegar overpowers the stevia in their mix. But those ingredients seem to do something good when mixed with citrus fruits at low levels. I suggest only using 0.1-0.5 % and only with citric fruits