It really depends on what kind of smoker your friend is. Cigars kept outside of a humidor may last for 1-2 weeks depending on the climate, but you have to make sure they are kept in a sealed  plastic bag. If you know he is a heavy smoker and that he will smoke more then a box in 2 weeks then get him more. I would say a good solution for you is to get someone else to buy a humidor and then you will have great presents to but him each year.