When we signed up for our Zone Pass back in 2014, Thousand Trails included the Encore South Lake Tahoe, CA campground as one of our resorts and we enjoyed a 14 night summer stay, completely free of charge.
Check to ensure you pay only one annual fee for the Zone Pass (USD$670) and you will have no further commitment beyond the first year, should you decide not to renew.
Unless you are an occasional/vacation RVer that doesn’t plan to stay at Thousand Trails campgrounds for more than say 30 nights a year, you are better off considering the Thousand Trails Zone Pass for a one year commitment only.