- "What are you doing?"
"Going to find Ray; same way I found you."
"Yeah; the only difference is Ray doesn't have a body."
"So, let's go find his soul."
"His soul token. That's the currency in hell. While a soul is being tortured, then its token is traded around town like money; as long as you have it, then you always have access to the soul."
- —John Constantine explains to Nora Darhk that in order to find a soul in hell, they need that individual's soul token.[src]
Soul tokens are currency used in hell.
When Neron took over Ray Palmer's body in 2019, this sent Ray's soul to hell, and John Constantine subsequently went to hell to save Ray. A short time later, John was joined in his quest by Nora Darhk (with Nora being sent to hell after Gary wished for Nora, being his fairy godmother, to help Constantine rescue Ray). After Nora found John in hell, he explained to her that because Ray's body was possessed by Neron back on Earth, they'd need to find Ray's soul token in order to find his soul in hell. Since Neron was the one possessing Ray's body, Constantine knew that Ray's coin was most likely in Neron's vault. After enlisting the help of Astra Logue (who'd been sent to hell as the result of John Constantine's attempt at an exorcism gone wrong (or, in Earth-Prime's timeline (which existed in place of Earth-1's timeline due to the fallout of the Anti-Monitor Crisis), the consequence of John's attempt to resurrect Astra's dead mother; Natalie Logue)) to access Neron's vault at the soul exchange, the trio broke into the vault, and while Nora and John searched for Ray's coin, Astra stole a number of other coins for her own ends. Using Ray's token, they were able to find Ray's soul in hell. After this, John and Nora were transported back to Earth; with Ray's soul coin now in their possession, as that was the only way for Ray to travel as long as Neron was using his body. After Neron was expelled from Ray's body and defeated, John used the coin to return Ray's soul to his body.
A short time later, in hell, Astra brought all the coins she'd taken from Neron's vault to the desk of the soul exchange; releasing the souls back to Earth. This caused the souls she freed to return to their bodies; resurrecting them a short time after their deaths, bringing them to the Legends' attention. Because their soul tokens remain in hell after these "Encores" are resurrected, they are nigh impossible to kill. However, certain weapons infused with hellfire can kill them. In addition, if Encores fail in their mission (being sent back to Earth in order to send more souls to hell, with those souls then becoming Astra's property; making her rich and powerful, with her goal being to tear control of hell away from the Triumvirate of Hell; wishing to rule hell herself), Astra can use their soul tokens to drag them back to hell to torture them as punishment for their failure.
Some time after being sent to hell, Astra got a hold of John's soul coin (with John's soul having been condemned to hell when he accidentally damned Astra there; thus the reason for his soul coin being in hell, even though John hadn't died yet) and, with help from Lachesis, messed with gears inside the chip, using it to speed up when he would die; making cancer that already existed in his lungs as a result of John's smoking suddenly get bad enough that he was severely weakened and at the brink of death. When John tried to go out on his own terms (drinking poison before the cancer would kill him), Astra met John in his own personal purgatory, which took the form of his house. Seconds before John died, he convinced Astra to let him live by telling her he could fix her family (planning to use the Loom of Fate, though he didn't tell Astra about the Loom). Astra then moved back the setting on the coin (reversing his accelerated lung cancer), but kept it with her as leverage; stating that she could kill John whenever she wanted and that he didn't have time to dawdle. John then regained consciousness back on Earth.
After finding two of the three pieces of the Loom of Fate, Constantine attempted to utilize a spell to summon the ring that disguised the last piece directly to his house due to the nature of the spell used to hide the final Loom fragment. Still recovering after a near-fatal encounter with the Fate Atropos, Sara passed out when Constantine tried to use a spell to borrow energy from each of the Legends in order to retrieve the ring. When Sara collapsed, Ava and Charlie ran to check on her, causing the whole group to lose focus. This kept the spell from working as well as it should've, and as a result, the spell did draw the ring to the house, but in the wrong time period. When the circle the Legends had formed broke ranks, John and Zari fell through a mystical portal that had suddenly appeared; ending up in 1910 in the building that they knew to be Constantine's house in 2020. Sensing what had happened, Lachesis, having stolen Astra's collection of soul coins that controlled the Encores Astra had resurrected, sent several Encores through time to 1910 to retrieve the ring. In exchange for their successful execution of this task, the one that brought it to Lachesis would be free to return to living life on Earth as they pleased. However, all of these Encores were killed; either by them turning upon each other, or being killed by Zari and John. Soon after these Encores were eliminated, Zari and John found the ring. A short time after this, the duo's teammates arrived; collecting the Encores' hell weapons to have on hand to deal with other Encores they expected to encounter later.
Meanwhile, while John and Zari had been stuck in the past with so many Encores coming after them, and also being frustrated that Sara's condition had left her in a coma, Ava decided to take matters into her own hands. Intending to go after the Encores at the source, she had Gary take her to hell so she could kill Astra (bringing along a hell sword the team had previously acquired). However, when they confronted Astra in hell, she assured them that she hadn't sent any other Encores after John since she'd last spoken with him. She then went into her personal safe to show them that all of her soul coins were still stashed there; only to find them missing. She soon realized that Lachesis had stolen her coin collection. Ultimately, Ava ended up convincing Astra to come back with them to the Waverider; encouraging Astra to aid them in their quest to bring her mother back with the Loom. Astra agreed; bringing John's soul coin, which she kept around her neck (though Lachesis had briefly stolen it along with the rest of Astra's soul tokens, and while Astra did reclaim John's coin, Lachesis kept the rest of them), with her.
In an alternate reality the Fates created with the Loom, when the Legends infiltrated a history museum Lachesis had constructed (dedicated to the idea that free will only caused chaos), Lachesis used several of the Encores' soul coins to animate statues of the respective individuals in the museum to battle the team. The Legends then obliterated them using the stash of hell weapons the group had stockpiled.
After the Legends defeated the Fates, (but not before Lachesis convinced Astra that bringing the latter's mother back was pointless, as it would just cause her to go through the pain of losing her mother again at a later date to illness or old age) Astra decided to live in Constantine's house, where her mother's spirit resided. She then gave John his soul token as rent.