Hub sticking - friction Bike I got used and happy with the price for frame alone but I don't know the history.  

Kris King hub with significant drag. 
With cassette off and just a rim if spin it hard I get 5 revolutions. 
I have a backup wheel and if I spin it hard I get 50 revolutions. 
I can feel a lot friction in the hub.

What should I do?

It is laced up to some nice Velocity rims.
Probably you need to service that hub - or get it serviced by your LBS.  That much drag means that either it's full of dirt, or the grease has completely dried up or water contaminated, or the bearings have collapsed.

None of those are likely to be fatal, but you would be well advised to open that hub up and clean it out, check the bearings, and re-grease it.  Or have your shop do it for you.