gasoline in 5 gal clear plastic jug, OK or not OK?

Almost all 91/93 octane around here is no ethanol. There are even a couple of stations that have 87 octane with no ethanol. Yes you pay a price of about 20 to 30 cents a gallon more for the low octane but how much gas do my small engines use? Lawn mower hasn't been started in 3 weeks.