SQL Prompt v10.3 and later will no longer support SQL Server Management Studio 2012 and 2014.
Earlier versions of SQL Prompt will continue to work in SSMS 2012/14, and you can keep using them for as long as you like, but new fixes and features will only be released for newer versions of SSMS. The final version supports SSMS 2012/14 can be downloaded from here.
SQL Prompt will continue to support SQL Server 2012 and 2014 - you will just need to connect to the server using a newer version of SSMS (2016 or greater).
How to update to a newer version of SSMS and continue getting SQL Prompt updates
New versions of SQL Prompt will work in SSMS 2016, 2017 and 18. The latest version of SSMS is available as a free download from Microsoft here. This version of SSMS works with all supported versions of SQL Server (SQL Server 2008 - SQL Server 2019). Additionally, SSMS 18.X can be installed side-by-side with older versions of SSMS.
SQL Prompt only registers itself with SSMS on installation or upgrade. After installing a new version of SSMS, you will need to reinstall (or upgrade) SQL Prompt to be able to use it in the new SSMS version.