When you purchase a training subscription for your team or corporation, learners have access to their assigned training as long as the contract is active.  The only time that a learner loses access to their training records is if they haven't accessed a course for two years.  Periodically we clean up our database and we remove courses from learners who haven't accessed the training for the past 24 months.  We always notify administrators when we will be doing the maintenance.  When training is assigned, the administrator does need to select an expected completion date, but learners have access to the training beyond that date.
When you purchase credits for individuals through our online store, the learner has 30 days to complete the training from the date that they assign the course.  After 30 days the course cannot be accessed unless Course Reactivation is purchased.