Pansies are meant to be outside. Pansies are surprisingly cold-hardy and their bright faces can bloom all winter long — at the very least, they wait out the cold to bloom again with the first warm spell.
Pansies need at least six hours of sun; plants growing in shade will produce fewer blossoms. They also need good drainage. If the soil stays wet and soggy through winter, the plants may rot.
Removing the faded blossoms will stimulate flower production.