What is the shelf life of these fungicides, and if they buy a fungicide, take possession of it and don't use it, can they store it for next year or the year to come?

Don't keep them on the shelf more than two or three years, and keep them at room temperature, so you need really good storage facilities and areas where you don't get any frost. – Palle Pedersen

If the section 18 label expires while product is being stored it would not be legal to apply for soybean rust management. – Chuck Eckermann