How Long Can I Keep A Cigar In A Storage Tube Or Case?

Let's say you want to store some quality cigars over a period of time.  Can you store a cigar?  How long does it stay good?  Where do you begin?  It really depends on your primary method of storage.  If you have a cigar humidor that is airtight and properly humidified then your cigars can last forever.  Even today, some cigars from the pre-WWII era have been smoked and enjoyed.  
The area of the humidor is important, as well as the temperature and humidity.  Some cigars age well, but not all aged cigars will be a great smoke.  A controlled environment is best for the natural aging of cigars.  Under-humidification and over-humidification are risks, though the former is less severe than the latter.  The loss of oil in the cigar is what will affect the taste.  
Remember that even if a cigar becomes under-humidified, it can still be brought back to normal humidity.  Once you over-humidify the cigar, you ruin it.  The loss of oil and the development of mold will be your biggest threats.  If you store a cigar in an ordinary jar you will probably only save it for about two weeks.  After this, it will dry out.  If you keep it in a sealed room, at about 70% humidity, and a temperature of 17 degrees Celsius, then it should continue to be smoke-able for months on end. 
An environment without humidity is not feasible, because the dryness will eventually dehydrate the tobacco.  Whereas cases have humidification systems built in (beads or sponges), ordinary tubes for storage do not usually have this provision.  If you do not have any provisions for storage, buy your cigars for quick use within two weeks! 
A storage tube is a cigar shaped tube that can accommodate one cigar at a time.  If the cigar is properly handled it will age very well inside the tube, provided you keep the tube closed.  However, once you open the tube the lifespan is significantly reduced.  The cigar quality is reduced as well because of all the dry air.  What is so special about the tube?  This storage vessel has cellophane and aluminum inside, both of which help to keep the cigar fresh.  It's not as good as a humidification system, but it works.  The tube can preserve a cigar's life for several months.  Other options to explore include cork stoppers.  These preserving devices can help keep opened cigar tubes fresh for several months as well.  Always take care of your cigars, as the taste and scent of a genuine vintage cigar is worth a little preparation.