There are 7 things all living things must have:
All living things are formed by cells.
All living organisms reproduce.
All organisms adapt to their environment (go through evolution).
Heredity is also an important characteristic of living organisms.
All organisms either grow or develop in some way (they are not the same their whole life).
Living things have a metabolism (a process in which organisms obtain nutrients, either from organic or inorganic matter).
Homeostasis is also an important, but less known characteristics of living things. It consists of the ability to regulate certain things in the organism's body.
Some scientists also consider response to stimulus as a "must have" characteristic.
There is also an important debate between scientist whether to classify a virus as a living organism given they have some characteristics, but not all.
Hope it helped,
Happy homework/ study/ exam!