Buy agave nectar at your local natural or health food store. It may be labeled as agave syrup. If the agave nectar is in a sterile squeeze bottle, it is fine to use from that bottle. If you have to purchase agave nectar in bulk, you must store it properly.
Transfer the agave nectar to a sterile, air-tight glass jar, ensuring any spills are wiped off the sides of the jar. Like any sweet food, agave nectar can attract ants if not cleaned up.
Store the agave nectar in a cool, dry place. Depending on the temperature of your home, a cool dry place could be the kitchen counter or in a cupboard. Agave nectar can be stored in the refrigerator, if desired.
Store the agave nectar in this manner indefinitely. It can last for more than a year, like honey, but does not crystalize like honey.