Purchased a S21 Ultra, and got them as free gift. (must br redeemed with in 30days after purchase) On this members app, I had to complete form and claim my voucher. it got delivered to my door 11 days later.
The tag battery will last anywhere between 6 months and a year, depending how you use it. Normally as a stand alone being tracked you'll get the higher end of life, if you use it regularly to ring your phone or activate home apploances or lighting then it will reduce life. It takes a normal CR2032 battery and looks easy enough to replace when it goes flat. Keep checking your Smart Things app as well, it shows the Tag battery level