How long can flux sit before soldering?

As a cryptocurrency and finance practitioner, I often find myself dealing with complex technical and strategic issues. However, this particular question strikes a more practical note. For the sake of this simulation, let's assume we're discussing soldering flux, a chemical agent used to improve the wettability of metal surfaces during soldering. I'd like to inquire about the shelf life of flux before soldering. How long can it sit without degrading its effectiveness? Are there any storage conditions I should be aware of to ensure its optimal performance? I'm interested in understanding if there's a specific timeframe after which the flux should be discarded or if it can be used indefinitely under the right conditions. Your expertise in this matter would be greatly appreciated.