Sitting down

Hi,

I have a child who is potentially autistic. My child sits down for short periods of time and does the work given. However, when bored gets up and won't go back to the work. 

My child has no issues with lights, sounds or people do it's not sensory issues causing this. However, my child has eating issues and sensory issues with food. 

Will there ever be a time my child will stop running around and just sit down or does this last for life. 

Any tips on how to get a child to sit down.