Version 1.2.3 of Stay is now available and can be downloaded here.
Please note that the process for granting Accessibility access to Stay has changed on Mavericks. There is a guide to the new process available here.
Stay 1.2.3 will only run on versions of OS X from 10.8 (Mountain Lion) onwards. Stay 1.2.2 remains available for use on OS X 10.6 and 10.7 and can be downloaded here.
The App Store version of Stay 1.2.3 has been submitted to Apple and is currently awaiting review. The non-App Store version of Stay honours App Store purchases and will run fully registered, so App Store users who wish to upgrade to version 1.2.3 immediately can simply download and use the non-App Store version of Stay.