In Configuration > My System go to the 'ODW' tab:
If you have a subscription that contains ODW, then you will see this tab. Within this section you can choose to enable ODW imports, i.e. store data longer than the seven-day retention period allowed within the runtime database.
Once you have enabled ODW imports, you can choose to set the retention period ' i.e. 12 months, 36 months, etc. You can also choose to enable an 'Extended Import', which means that instead of just storing summary data in the ODW, Opsview Monitor also stores every service check and performance plot in a non summarised format. This also has its own retention period.
Finally, you can choose to import all Hosts/All Service Checks, or uncheck the box to choose to store long term data about a specific set of Hosts/Service Checks as shown below: