Any member can be authorized to spend up to the full credit limit of this Enterprise Account.  

For instance, if the account has an available balance of $1000 and there are 4 members, each member can have up to a $1000 available balance.  However, once the account reaches $1000, even if member #4 only spent $50, he will not be able to purchase until the account has been paid.  

Account balances will automatically be reduced when payments are made. To request an increase or decrease in the amount of the credit line, please contact your account representative.

Now you can also set member balances to less than the total of the account to throttle purchasing of a certain member.  Take the same example as above, except that only one member has a $1000 available balance, and the others only have $100.  If If members 2,3,and 4 spend their $100 on the first day of the month, then member 1 will be the only person who can continue to purchase, and only up to $700. To allow the other to keep purchasing, the admin can either increase their budget, or reset their purchases for this period back to $0.

Many groups use this to allow members to make smaller purchases without asking for approval.  "Instead of spending 4 hours building another mailbox, simply go any buy one for $30 from TurboSquid."