We give all of our free HelloSign users three free documents to sign/send every month. Those documents renew every 30 days from the day you originally sign up. They do not refresh based on the calendar month.
For instance, if you signed up for HelloSign on January 17th, your pages will renew every 17th of the month (give or take a day for the longer months).
If you used your documents on January 17th, 20th, and 21st, your pages will not renew on February 1st. You will still be out of docs until they renew on February 17th.
Check to see which day of the month you signed up for HelloSign, and that's when your three free docs will renew each month.