Back in the 1950s, the New Yorker offered a lifetime subscription for a few hundred bucks. My Dad promptly paid up and still gets his copy every week nearly 60 years later.  These days, I’ve noticed more and more paywall sites making the same offer.Initially, most were stock investing newsletters in PDF or email format with a companion site that’s mostly shovelware (little more than searchable back issues.) A lifetime subscription would be several thousand dollars. Most publishers who tested it did so for a quick cash hit. But they learned that lifetime subscribers are also the easiest people to sell additional products to, such as seminars, cruises with celebrity advisers, and even additional sister-publications. So, selling lifetime accounts takes a lot of risk out of launching additional products.Now, several membership sites have a new twist on the lifetime offer. Instead of using it as an upsell for their most fervent fans, they make lifetime their *only* offer — no monthly or annual fees, lifetime only. And the price is reasonable, what you might expect to pay for a one-year subscription. Examples range from Arena Pwnage, a tips site for World of Warcraft players with a $37 lifetime membership, to Elite Parrots Club which gives you lifetime access to parrot training info for two payments of $47.77.At first glance this seems counter-intuitive. Consumers are increasingly gun-shy of online memberships and subscriptions because of the difficulties some have had with unscrupulous autorenew merchants. So why not make your offer more attractive removing the word “membership” altogether and just saying it’s a one-time only charge — just like buying an ebook?My take? In my experience, the split second a customer is no longer an active customer of yours, the likelihood you can sell them anything ever again takes a sharp dive. For example, you’ll get a far higher conversion rate telemarketing expiring subscribers the week before their subscription ends than if you call them the day after.But if you’re a member for life, then I can always market to you as a current member. I suspect the conversions go up accordingly.