Vilnius bus station has only manual luggage storage.
If you want to use an automatic left-luggage lockers, then you should go to the railway station, it is located not far from the bus station. You can read more about automatic luggage storage here:
To leave one item per day will cost you 3.5 euros (in 2022)
Luggage storage is open every day:
from 5:25 to 21:00 every day except Monday and Sunday. These days the luggage room opens at 7am.
If you want to find luggage storage at Vilnius bus station, you need to exit the main building in the direction of the bus platforms, go through them to the end until you see a small building. There is a parcel dispatch and a left-luggage office.
Location on the map: