If you grow your lemon tree indoor you should consider placing it near a West window and move it outside in full sun over the summer. Mist the foliage between two watering in the winter if the temperature grow over 15 Celsius degrees (60 F).
A root rot may occur if too much water remain in the pot and a too cold water may cause the leaves fall so try to water them with room temperature water and not more than needed.
If the tree become too large for its pot you can transplant it at the end of winter in a bigger pot. They can reach 1-2 m even if grown in pots, so consider a space big enough where to place the tree. It can survive up to 10 years if grown in pot.
Considering the dimensions of the tree and the pot you might wish to think to plant the lemon tree in a pot that have roles under so you can move it easier where you want to put it and also when is time to take it out for summer.