|We live full-time in our RV, and belong to several of the Discount Camping Clubs (Recreation USA, Escapees, Passport America, Good Sam, etc). We have Lifetime Memberships with each organization.
We originally went the 'lifetime' route for financial reasons - once purchased the membership never expires. In two years time, we saved enough money on campground fees to cover the initial cost of Recreation USA, Passport America and Good Sam. The Escapees program will take us a bit longer - as we don't seem to stay in their 'system' nearly as often.
Discount Camping Clubs provide excellent value - provided you decide to stay in RV Parks which offer the discount. However, the discounts provided work primarily on 'short term' stays. If you plan on staying several weeks (or a month) at a specific place, the monthly rate is already the lowest price). Most limit use at a specific park based on the RV Park's own set of exclusions (e.g. Not Valid on Talladega Race Weekends, Fourth of July, etc.)
For us, these programs offer great value. Of course, YMMV.