does plant food go "off"

hi, i have some plant food that i was going to give my mate, trouble is i havent grown anything in nearly 4 years, i have opened the bottle and used about a 1/3 will it be fine to use or should he buy some new stuff, its liquid form for flowering and has bloom on the label, i think its called ionics or something like that, thanks in advance

if it was sealed tightly it should be fine

yeah the lid has been done up the past 3-4 years i just didnt want to give it to him if it had gone bad,
thanks for the reply

if it smells alright, it should be fine. As long as it doesn't smell sour.