A bound state represents a balance between repulsive kinetic and attractive potential energy. In a hot quark-gluon plasma, the interaction potential experiences medium effects. Color screening modifies the attractive binding force between the quarks, while the increase of entropy with separation gives rise to a growing repulsion. We study the role of these phenomena for in-medium binding and dissociation. It is found that the relevant potential for binding is the free energy ; with increasing separation, further binding through the internal energy is compensated by repulsive entropic effects.