I found a flask with weed I put in ethanol about more than 3 years ago. It's been kept cool enough and I know how to continue with the process to skin it down to oil, but I doubt if the cannabinoids are worth anything at this point. Anyone knows what happens to weed in ethanol after 3-4 years aside from being chuck full of chlorophyl?
If it is in the freezer at -40, you can take it out that long with little degradation.
If it is not actively refrigerated, there will be breakdown. How much depends on a number of factors. Temp, light, quality of bud, trim of bud, amount of water in eth, etc. But a lot of the breakdown that occurs is oxidization, and there really should not have been any oxygen present in a sealed jar of Eth.
You will want to properly winterize this before extraction, probably multiple passes. Terps are gone at this point tho.