Qualifying Credits is a clarification on Active TSAs since all TSAs don't have the same monthly subscription and they shouldn't count the same.  So monthly subscriptions of $99.95 = 1 credit and monthly subscriptions of $49.95 =.5.  

This means that in order to qualify Sapphire via Active TSA credits you would need to maintain either 100 people who have monthly subs of $99.95/mo or 200 people who pay $49.95/month.