Zinc air batteries use air as an active ingredient in fueling the battery. The tab provides a seal that ensures freshness until the time of use. Once you un-tab the battery, the air from outside of the battery begins to react with the zinc inside of the battery, this reaction is what powers the battery. To properly activate the battery, remove the tab and wait one minute to allow air to fill the battery, then, insert the battery into your hearing aid. Note: replacing the tab when the battery is not in use will not extend the battery life.
When tab is removed and the battery has been aired up properly, make sure that you are not forcing the battery door closed. Check that the battery is inserted correctly before closing the door.