Question:
When a user sends a document as a link and selects a month, does the link expire in 30 or 31 days?
Answer:
From the code standpoint, one month using Send as Link is the same day of the next month, not exactly 30 or 31 days.
Example, one month from July 2nd is Aug 2nd, one month from Feb 4th is March 4th, and one month from January 31st is Feb 28th or 29th, depending on the year.
Related Documentation:
Vault Send As Link Documentation: