There two different databases where events gets stored in Spectrum , DDMDB and reporting db
Events are retained in DDMDB only for last 45 days by default, events are available in reporting db for much longer duration and can be used for historical reporting . If you are looking to run historical reports for events , reporting db is the best place to look for . Events are not moved to trash after 45 days , they are available in reporting db for long term reporting , if you are looking to run reports for last 1 year , make sure that you retain the data in reporting db