When money is created for use in a society its creator must somehow place the money in circulation. In doing so he exchanges newly created money for something real such as property, goods or services. When a pure gift, the exchange may not be in tangible goods or services but in some abstract satisfaction. The creator can also lend money into circulation. He can exchange it for some sort of promise that the money will be returned to him.
Money placed in circulation by spending or giving goes into use with no strings attached.
It is debt free and never needs to be paid back. Having been paid for already with property, goods, services or other satisfaction it continues to circulate permanently, facilitating business transactions. Money loaned into circulation is not permanent money. It is a debt owed. Debt based money must be returned to the creator bank, where it is recorded as a bookkeeping figure which is gradually extinguished as the debt is repaid.