Hi - When users capture data in QuickCapture, it is sent to a feature service. If this feature service is in ArcGIS Online, the storage of submitted features will consume credits. However, this is very minimal, see: https://doc.arcgis.com/en/arcgis-online/administer/credits.htm for more information.
The data in a feature service will not get deleted until a user with permissions chooses to do so. Feature data captured from a QuickCapture project will never get automatically deleted.
Location tracking is different, it is a platform capabilty that records where your users have been. These track points don't consume credits, but they do get automatically deleted after 30 days if using ArcGIS Online. If using ArcGIS Enterprise the tracks do not get automatcially deleted.
You can back up these tracks in ArcGIS online if required.
I hope this helps, please let me know if you need further information.