Sun: it prefers full sun.
 
Directions for growing indoors:
Most people aren’t aware that the lack of sunshine is the most common reason for a rosemary plant growing indoors to die. Often, rosemary plants are brought indoors without any acclimation. They go from six to eight hours of strong, direct light to four to six hours of weak or indirect light. The rosemary plant is unable to produce enough energy to stay alive on this amount of weak light and simply dies. The first step to preventing rosemary light starvation is to put your rosemary on a sunlight diet before you bring it indoors. Several weeks before you plan on bringing the rosemary inside, move the plant to gradually shadier areas of your yard. This will force the rosemary plant to grow leaves that are more efficient at turning light into energy, which will help it cope with weaker indoor light when it moves inside. Once your rosemary moves indoors, make sure that you place it in the brightest window in your house, which is normally a south facing window. If your rosemary plant is not getting at least six to eight hours of light a day, place a lamp with a fluorescent light bulb as close as possible to the plant to supplement the sunlight.

https://www.gardeningknowhow.com/edible/herbs/rosemary/grow-rosemary-indoors.htm