How long can we store material from camera surveillance? 

If you use camera surveillance that allows recording of the footage, you must not store the recorded material longer than necessary with regard to the purposes for the surveillance. This means there is an obligation to strive for the shortest storage period possible. The European Data Protection Board's recommendation is a storage period of three days, but if you have clear and identified needs for a longer retention period, that may be allowed.

Limit storage time (in Swedish)