I have 3 computers. Windows 7,Windows 7 Windows 10. I have emclient on one computer that works. I need the same program on all the computers so I can check my email in the same way. I have ordered pro I have asked for help and get a run around. The only reason I am trying again is because I have used emclient for years. It never was a problem before. Now it is Help !
Make a backup using Menu > Backup from eM Client on the computer where it is working.
Now copy the backup zip file to the other two computers. Install eM Client on those, and when the application starts, cancel any setup windows and go to Menu > File > Restore. Point to the zip file you copied to that computer and it will restore all your settings and data.
As long as your email account is setup as IMAP or Exchange, the three computers will sync their messages.