This situation is one of bailment for reward because both the bailor and the bailee benefit from the bailment. In this kind of bailment relationship, various rights and duties arise. As with gratuitous bailment, the primary responsibility of the bailee is to take reasonable care of the goods. But in addition, the bailee must account for any profits they make from the bailment, they must return the goods to be bailor in accordance with any instructions (or on demand), and must return the goods in the same condition they were received - except for any reasonable wear and tear.
Taking reasonable care of goods requires that the bailee must keep them in an appropriate place and protect them against any unexpected dangers. Normally, a bailee won't be responsible for any loss or damage to the goods, as long as they have taken reasonable care and have only used the goods in an authorised way.