SQL 2012 database table purged

look at this link for different methods and explanations:

http://sqlmag.com/database-administration/4-ways-purge-non-partitioned-data

Do you know when was the last time the table had all data?

use the free https://www.red-gate.com/products/sql-development/sql-search/ and search for your table name. you might find a stored procedure purging data

I didn't really check when it had all data, but the latest data is 14/01/2015 which is a about exactly 3 months ago which make me think that there is a purge for all data that is older than 3 months.