It's a rebranded Digipass GO 6 which has an expected lifespan of 7 years, depending on how many times the button is pressed.

You should go a low battery warning before it runs out and it should say BATT 05 where 05 means approximately 5 weeks remaining. The number will go down as the weeks remaining drops, although when you get the warning probably best to replace ASAP.

I still have my original Final Fantasy XI authenticator (before XIV!) and that still works, although I don't really push the button any more as I moved to the software authenticator a long time ago (and now the Google Authenticator one as that's even more convenient).