What is Promissory notes execution?

Execution of Promissory notes is an automated process made by Tokpie exchange during the maturity day to reach the following targets:

• Deposit Principal Cryptocurrency on accounts of all users who have expired promissory notes on their balances.
• Withdraw Principal Cryptocurrency from accounts of all users who issued such promissory notes, but have not yet settled them. 
• Exclude executed Promissory note title from circulation and add a new one with a new maturity date.