Apparently on this planet scrip was invented before money. Women - who used to almost all own their own herds, before specialization got really going, though they sometimes paid others to mix their spren in with the other herd and look after them both together - wanted to be able to send their mates and kids on errands. They wrote IOUs entitling the bearer to some meat belonging to the issuer, since in this era meat was more of a commodity - this was before they had the technology to raise spren away from the smell of people, so it all tasted about the same and nothing else they did made all that much difference in its quality. But bearers didn't always want to redeem that right away, and scrip has an expiration date - you don't want someone to come knocking years later demanding six hooves pronto even when you've since fallen on hard times. So they'd trade it to people who did want meat within the relevant time frame. Cash was invented later.
The advantage of scrip over cash is that if the issuer is suspicious of you she can check your story and make sure she approves of all the steps that led to your possessing her scrip. If you stole it, you can't redeem it. If her mate was spendy in ways she doesn't approve, you can, but she will know not to trust him on errands in the future. Cash is far harder to trace because it doesn't expire and it doesn't have stamps on it saying what steps it's passed through since issuing. Sellers will take cash even under dubious circumstances but may refuse scrip if it expires before they can redeem it, or if they suspect the issuer will have left instructions at the bank that will render its redemption disputable.