There are many different things you should be doing to properly store your spare electric motors. Spares should be stored in temperature controlled environments. Shafts should be spun regularly to keep the bearings lubricated. Electrical testing should be performed on a regular basis to ensure motors are in an operational condition. Some companies even pull motors off the shelf and test run (apply voltage) them on an annual basis to ensure they are ready to go when needed.
Want to know more about storing spare electric motors? Visit HECO's helpful blog, Here You Go: