How do you know if you are in someones will?

Answer 1

You don't unless they tell you. There is no requirement for them to tell you. When the will is brought to probate after the testator's death, the court requires that all beneficiaries of the will be notified. Until then, you simply don't know.

Answer 2

Typically, the person creating the will (the testator) will inform you if you are named as a beneficiary in their will. After their passing, the executor of the will is responsible for notifying beneficiaries of their inclusion. Additionally, you can inquire directly with the executor or the testator's attorney to find out if you are named in the will.