it depends on how well it has been stored.

Has it been sealed airtight?
Nitro fuel has a tendency to absorb moisture from the air and the fuel will also evaporate leaving you with a higher percentage of oil, and a lower percentage of fuel, if it has been stored well sealed, and not exposed to extreme high/low temperatures, then it should be fine.

For a while now family and work commitments have resulted in me running my cars/trucks twice in the last 18 months or so, and I am still using the same fuel with no problems. I always put the bung back in the bottle before putting the lid on, and the bottle is only ever open for as long as it takes to fill the squeezy bottle, it is stored in an indoor electric cupboard with no natural light, no heaters, and on a shelf so that it is not in contact with the floor.

Try it, just make sure you use after run oil to ensure no water can harm the engine, but if it runs ok, then no problem, if it doesn't then get a new bottle.....