Nobody knows how long it will last. Depends a lot on how much it is used, quality of the battery, etc. I have never killed one on any car even with over 10 years on it. If you look on the back of the remote it will tell you what battery it takes. Mine is a 2025. Cobalt is a 2032.
I've replaced a few in my Volvo remotes just to make sure I'd fixed an intermittent operation problem, but I'd guess that battery power hasn't been any part of the issues. Removing the battery, cleaning it and the contacts, and making sure the contact spring pressure is good should be enough. A quality battery should last 4-5 years at a minimum.
BTW, I've had good luck with battery packs from places like the Dollar Store for 2016, 2032 and 357 batteries - so they last only a year, at 10-20 cents each it's a no-brainer. I got tired of buying $3-4-5 batteries for things that ate them up.