Activate Warren Soultrader by paying 1 life and sacrificing the persist creature.
When the persist creature dies, its persist ability triggers, returning the persist creature from your graveyard to the battlefield with a -1/-1 counter on it.
When the persist creature enters, Ajani's Welcome triggers, causing you to gain 1 life.
Resolve the Warren Soultrader ability, creating a Treasure token.
When the Treasure enters, Mm'menon triggers, putting a +1/+1 counter on the persist creature.
Repeat.
This clever loop turns a self-sacrificing engine into a perpetual fountain of resources, starting with Warren Soultrader to convert creatures into Treasure tokens at the low cost of a single life point. As those Treasures enter the battlefield, Mm'menon, Uthros Exile notices the new artifacts and counters the natural decay of your persist creatures by placing +1/+1 counters to immediately neutralize their -1/-1 counters. Meanwhile, Ajani's Welcome passively buffers your life total with every creature that returns to the field, offsetting the costs and keeping the whole machine running indefinitely.