At that point why not just sell lifetime memberships by default?

But then that's not a stable SaaS business.

There's a pretty reliable flow of new people aging into the dating world or entering it for the first time.

In any event, "pay a regular subscription for X years and free thereafter" is just a lifetime subscription paid in installments, not a fundamentally different business model.

It seems different. You may no longer need the service after a few mnonths. Or decide you don't like the service, and look for another one. In either case, you pay far less than what you'd pay for lifetime service.

Upfront price

Honestly, I think this is a great idea. It would probably cost next to nothing but would work well as a marketing ploy.