Get the application name
There is no perfmon counter that would you show you this information.  Why don't you just pull this directly from SQL Server (at least as how SQL Server sees it)?

select
    session_id,
    program_name
from sys.dm_exec_sessions
where is_user_process = 1;


If you're looking for data collection, you can periodically run this and store the output of the above query (or a variation of it, maybe with aggregating by program_name instead of grabbing session_id, depends on really what you're looking for) with a datetime stamp for subsequent querying.