All students taking PSF, PSM or PSPO courses accredited by Scrum.org are entitled to one free attempt at the relevant assessment. If the 1st attempt is taken within two weeks, and a passing score is not achieved, a 2nd free attempt will be granted. The exact time that this deal expires will be listed in the email you received from scrum.org. It is usually 23:59 UTC, 14 days after the password email has been received from Scrum.org.
If you do not take your 1st attempt within 14 days, you will be entitled to one attempt, which can be taken at any time and will not expire.
If you receive a 2nd free attempt, the 2nd attempt can be taken at any time and will not expire.