Time period in Export calendar

Hi

When you export your calender and make a URL to import in a personal Google/iCal/Outlook calendar, you have to indicate Time Period. The Time period provided is a year from the day you generate this import url. 

Does this really mean that after a year that link is obsolete? And the student has to do a new import? Or does the link stay dynamic as long as the student has an active Moodle account?