I was ambitious and made some homemade binder back in late July. But I can't remember how long it's supposed to be good for? I have a lot left, so I'd rather not throw it away if the age isn't going to affect the quality of my paints.
And YES, I have been keeping it stored in the refrigerator, which I know helps its shelf life. I just don't remember by how much.
I still have some gum arabic powder left, so I can make more if I need to. I'll just make smaller batches next time so less goes to waste if I can't use it all in time.