Free=2 Premium =6 Member=16 There is a place in the market place you can purchase additional character slots, but the price currently alludes me. It is rarely inexpensive though. Hope this helps.
Additional Character slots can be purchased for 500 DayBreak Cash (PC) or 500 Marketplace Cash (PS). 500 DBC or 500 MC costs $5. The default number of character slots for a free account is 2. Purchasing $5 worth of marketplace items unlocks Premium which has 6 character slots. An additional 16 character slots can be purchased.