If you want additional elists you need to register additional accounts. There is no problem about having multiple accounts. I originally registered three in order to get free hit counters on every page of my first site.
Thank you so much for your quick reply! (i searched the site but could not find the answer).
Was the second account mailing list limited to 500 subscribers like it is for the free account? (i'm planning on getting the Pro soon, which allows for 3,000 to 150,000 subscribers).