I quality hot tub purchased from a legitimate registered dealer, not one you buy online or from a friend, should easily last 10 to 20 years or more. You simply need to properly maintain it during the months you are using it. Which means to make certain the pH, Alkalinity, Hardness, and Sanitizer levels are kept in line, changing the water when needed, and having it professionally serviced when necessary.
To extend the life of a hot tub we strongly recommendation not to leave your spa drained for any extended period of time. So, if you’re going to your second home for 3 months you are better off turning down temperature, locking down the cover, and let the hot tub filter and maintain itself while your away. Or hire someone to check on it occasionally.
Hot tubs sitting empty over long periods are the number one cause of service problems because pump seals, jet fittings, etc. quickly dry up and deteriorate.
In most cases it is less expensive to have a spa set at 80 degrees unused and covered for 3 months than paying to have it professionally winterized.
If you do have your spa sit empty for a while make certain to use HT Jet Line Cleaner to flush out all the internal plumbing lines of your spa because very likely they may have some bacteria and sediment in them.