I recently adopted my grandson... my daughter was an unfit mother so to speak.. I am getting support from the state for him does that ever stop? If so when should it?

Talk to your Social services agency, but generally support stops at 18 or when they finish High School.

The support that you're getting from the "state" should actually be coming from the parents. The state may be the ones collecting it (via wage withholding) and disbursing it but it is ultimately the parents' responsibility to pay, whether they've been deemed "unfit" or not. Normally it would stop when he turns 18 but could continue longer if he has special needs or is a full-time student.