Right now, if you set up a $500 coupon for staff to use on course purchases, it applies the coupon to each purchase. Therefore, every purchase has a $500 limit, rather than a cumulative total of $500.
There is no way to limit this coupon use per employee, without creating a coupon for every employee and limiting the number of times it can be used. The limit on number of times could mean they don't receive $500 in total for courses, or it could mean they overspend if every course purchased is a higher dollar amount but doesn't exceed $500 for the single transaction.
This makes managing a coupon extremely laborious, and with no way to stop an employee from purchasing additional courses beyond the intended limit of a cumulative total amount.