The length of time your lights can stay on will depend on how bright you have them set and how powerful the battery is. Sometimes the power source is built into the lights, but others can be plugged into an external power bank. The bigger the bank, the longer the lights will last.
Still, with most high-efficiency LED lights used in these products, you can expect your lights (like the Coleman string lights) to last for at least several hours. If you use a lower-power setting, some string lights can even last for days at a time, and features like built-in solar panels on the MPOWERED lights will only extend this time.