I keep one until the battery dies. Then I replace the battery with a second rechargeable lithium and a new watch band. By the next time the next battery goes dead, the case is shot, too. Make absolutely sure that you follow the battery replacement directions carefully, reading the directions fully BEFORE attempting it. There are very tiny parts that can drop out and easily lost.
I can taste metal in an acidic dish when it isn’t treated, but seasoning mainly makes the pan easy to clean.