In an email to users on Friday, Apple reminded Messages beta program participants that the preview period will end on Friday, Dec. 14, noting that the service will then only be available on OS X Mountain Lion.

AppleInsider Jim was first to note the upcoming closure, which brings the OS X 10.7 Lion preview service to an end.

Apple first introduced Messages beta for Mac in February, bringing cross-platform messaging support for OS X and iOS. As a replacement for the previous iChat application, Messages beta was meant to bridge the gap between Apple's computers and portable devices with "Messages Everywhere," a feature that allows users to start a conversation on one machine and move seamlessly to another.

In June, Apple cut off downloads for the beta in preparation of OS X 10.8 Mountain Lion, which replaced the beta service with the dedicated Messages application.