When you agree to play a match, it includes a match length. The next game in the match will start automatically when the previous game ends until the match is decided.
See the rules for match play:
http://www.bkgm.com/faq/Matches.htmlIf you want to play one game at a time, invite players to one-point matches. If you agree to play a longer match, etiquette demands that you either play it to the end or resign the match. You can offer to save and resume later, but only if you really intend to finish the match later.