Your mom licks your penis what should you do?

You should not allow this to take place as it is abusive. Tell your mom not to do it again as you know it is wrong ! If you are able to tell a relative of the abuse this should allow it to be stopped.

Not all abuse is by force or with pain involved !

This is sexual abuse and it's called Incest. It is illegal and immoral. No child should have to except it. There are places you can go and report it. You must not feel guilty about reporting this as it is not your fault at all. You will not get into trouble with the law for reporting it either.
You should not allow this to take place as it is abusive. Tell your mom not to do it again as you know it is wrong ! If you are able to tell a relative of the abuse this should allow it to be stopped.

Not all abuse is by force or with pain involved !

This is sexual abuse and it's called Incest. It is illegal and immoral. No child should have to except it. There are places you can go and report it. You must not feel guilty about reporting this as it is not your fault at all. You will not get into trouble with the law for reporting it either.