Provided you don't trash or handle your fly rod roughly it should last for many many years. In some cases a good quality rod can even can be passed down to your children or grandchildren with just a modicum of proper care and more importantly handling.
But fly rods do require some amount of care and maintenance to make sure they stay in tip top shape.
First for the proper handling of your rod; you should get a nice hard carrying tube for your rod. Be sure to measure it precisely so it fits snugly into the tube without any slop or room to bounce around back and fourth.
Fly rod tubes are more than just a piece of PVC pipe fitted together. For more details on choosing a a tube check out our fly rod carrying tube guide.
First of all you should check the guides on the rod carefully. The metal snake style guides on fly rods can get chipped which then cause them to drag and snag against the fly line.
This causes two problems: you won't be able to cast smoothly because of the drag where the line can catch on the snag and it will wear out your fly line quickly because of the abrasion to the slick coating of the line causing all sorts of issues.
So make sure all of the guides are in top working order and don't have any dings, chips or rough spots that can snag or catch the fly line.
In the event you do find a fouled up guide it is possible to replace them yourself or have them replaced by a professional fly rod builder. But replacing a damaged guide is not an easy process!
Repairing a bad guide will require gently slicing through the thread wrappings using a hobby knife or razor blade and thoroughly cleaning off the old glue finish. Next you will need a fresh batch of two part rod finish, a replacement guide and thread for wrapping. Wrap the guide on the rod, double check the alignment and glue using the rod wrapping finish.
As you can see, repairing your trout fly rod is not for the light of heart... and you can easily damage the graphite of the rod blank with the razor blade.
Sometimes the tip top on a rod can come off after prolonged use. This is not the end of the world and happens because the tip tops are simply glued onto the end of the rod without any wrappings and the adhesive can wear out over time.
To repair a tip top simply visit any sporting goods store with a good selection of fishing supplies and they will carry tip top adhesive.
The tip top adhesive comes as a hard stick, sort of like glue used in a glue gun. To fix the tip top simply clean off the rod tip blank to remove any of the old adhesive. DO NOT scrape or scratch the rod blank because this can damage or weaken the rod blank.
You apply a heat source like a lighter to the tip top adhesive stick to melt it, then smear it onto the end of the fly rod blank. Working quickly gently insert the tip top guide onto the blank and align it with the other guides. Make sure to wipe off the excess adhesive quickly that will come out at the end of the tip top guide before it hardens.
Any of the adhesive on the rod itself can be replaced but you will have to cut it off after it hardens to do so which you risk damaging the blank.
Finally you will want to take care of the grip and reel seat. On a good quality fly rod the grips are almost always made from cork, the exception tends to be those for salt water use.
After each time you go fishing be sure to inspect the grip and wipe off any excess dirt or debris from it and dry it off before storing in your tube or sock. 
You can use water on the grip to help clean it off but make sure that you dry it thoroughly before storing in your rod tube.