Special note on the bottom of invoice

Hello Managers,

Happy New Year. hope you all will be fine

how i insert a special note like expiry items or any note of this type in the bottom of sales invoice.
this note is permanent. i put it once and this print on all invoices automatically.

Create a custom field. See https://www.manager.io/guides/8941.
Make it appear on all sales invoices using Form Defaults: https://www.manager.io/guides/14059.