Payor (noun)
One who makes a payment.
Payer (noun)
One who pays; specifically, the person by whom a bill or note has been, or should be, paid.
Wiktionary
Payor (noun)
payer.
Payer (noun)
a person or organization that gives someone money that is due for work done, goods received, or a debt incurred
“the industry is one of the biggest payers of corporation tax”
“licence payers”
Oxford Dictionary