A very hard question to answer. Never could find anything on Easy Clean but for One Step which is about the same it says a couple of days in a dark sealed container or up to a month if refrigerated (warm before use). However one site warns not to seal in a glass container because it gives off gas and could explode. Never heard that one before, it got me thinking as I mix my Easy Clean in a glass 1/2 gallon jug and seal it.
Everything I read says Easy Clean and One Step are the same as OxyClean but without dyes or perfumes. As far as shelf life on OxyClean it says on their site to discard after 6 hours.
I make up 1/2 gallon and use it for that day and then dump it down the drain. To me it seems to get slimy after a day and seems to leave a slick coating on glass.