Hi, I see that you have no response to this. I have the same question. Normally NCH have been great for software, but I am totally confused with Express Invoicing and Express Accounts. In Windows I could download together and they link, as per the instructions. This is great to research for my clients, however I am on a Mac and downloaded both programs for my own use, but now find I can't link payments from the invoicing to the accounts. Very inconvenient. By the time you buy both programs you could purchase another basic accounting program. Why can things work on Windows and not on a Mac?
I am also confused over what the difference is between the free and paid versions, but suppose I will keep looking. Things shouldn't be so sneaky - it should be all out in the open and clearly stated - that's what the Department of Fair Trading says anyway. Wonder if that day will ever come?
Will wait for a response and hopefully a solution.