If you want to track when you replaced the battery, put a mark on the battery with the month and year so you know when it was replaced. If you cannot write on the battery, putting a hidden note under the memory panel is also an option.

Optional: Put a note on the RAM door out of sight or write when the battery was replaced on the new battery.

Push the tab on the battery in and then remove it. Put the new battery in the reverse way of removal. Once this is done, write when the battery was replaced (Example: 5/16) on the battery.