Yes, they do. In order to support data integrity and traceability, very few elements within SciNote can be deleted - most of them can only be archived.
Most of the elements in SciNote can only be achieved, so if you archive a task that contains files, it will still take up storage space.
The size of a file uploaded is limited to 50 MB on the free account and 300 MB on the SciNote Premium account. Your total storage space is determined by your current plan.