That depends on when you first bought the plugin in question.
If you bought your licenses May 1st, 2011 or later: FREE update. Simply grab the new installers for these plugins.
If your license was bought BEFORE May 1st, 2011: PAID update. Don’t worry, updates for one older plugins is only $20 or $50 for all of your Alliance plugins in one account. This includes updating bx_control V1, bx_dynEQ V1 and bx_digital V1 to the current, V2 versions.