Unless you use instant web publishing to publish it to the web (can be just your intranet and not available to the outside), you'll need to purchase a second copy.
I tried to use instant web publishing, but when I went to the address of the computer hosting the database I got a blank screen. I followed the instructions for setting it up.
File -> Sharing -> INstant Web Publishing
I clicked on the file - set All users - got a message that port 80 was already in use so set it to 591 (I forget where it told me to do that). Clicked OK.
When I go to the other computer and put in the url as shown on the IWP page I get page cannot be found message.
Any thoughts? If I have this set up correctly I can move these two computers to a location where I have a stronger wireless signal - do you think that is my problem?