Its good under those conditions. Taylor suggests one year for reagent replacement but some will last indefinitely under good storage conditions. I like to replace the pH Phenol Red yearly, but that is my OCD.
I’m curious about the same thing. I could either by 10 g on Amazon for approximately $9, or 0.25 pound which equals 113 grams for $29. Obviously the quarter pound is a heck of a lot better value wise. As long as I keep it indoors, in a dark space, away from any moisture or sunlight, I don’t see what is the problem; especially if I transfer it to a smaller container for regular use.