Cleaning agents themselves have a fairly long shelf life, probably a year or better. Tests have shown quaternary ammonium compounds to have a shelf life of well over one year in their ready-to-use state.
There are some variables such as water hardness and contamination of the product that could be of concern, but in most cases, the solution is used well before it has lost its effectiveness.
Isopropyl alcohol stays good for about ...
— Lynn E. Krafft
, ICAN/ATEX editor