emclient on two machines, neither gets all mail

My EMClient is missing some messages but if i go to google I see them.  I think it relates to having it installed on two windows pc’s (dual boot) for same accoiunts.  Looks like if one gets a msg when i go back to other it does not show up.  I can discontinue to dual use but how do i make one copy go get all or missing message headers.

You can only use one license on one machine (dual boot is considered 2 machines).  Since you are using Google, are you not also using IMAP?  If yes, then once you activate the license properly on the one machine, it should sync with the server and you should see all messages.