No! It's like salt. Does salt go off?
Unless moisture and water has got into the container, it should last until the container disintegrates.
Add a bit of Salty Shrimp GH+ into the RO water (go slow), stir it in, until it reaches 150 TDS. Keep measuring with the TDS meter you are getting. Doesn't have to be exactly 150 as Simon said.
If you have the tools for it and the patience, that is the best way. Or if you are like me, impatient, I add 25% of the new change water back into the tank every 20-30 minutes. So over the span of 2hours or so.