Are local folders considered to be an "account"?

I have 2 email accounts (1 Gmail and 1 local ISP) plus a bunch of local folders where I save emails that I want to keep.  When I go to set up eM Client, it lists my 2 email accounts and “local folders” in the list of which accounts I want to include, for a total of 3.  Do I need to purchase the Pro version in order to have my 2 email accounts and my local folders included?

No, the Local Folders are not an email account, so do not count. 

If you go to Menu > Tools > Accounts, and see how many email accounts are listed there, that is what counts. If you have exceeded the permitted limit, you will be notified by a pop-up when you start the application.