We study the evolution of heavy quarkonium states with temperature in a Quark Gluon Plasma (QGP) in terms of the in‐medium QQ T‐matrix obtained from a reduced Bethe‐Salpeter equation. The interaction potential is extracted from finite‐temperature lattice QCD calculations of the QQ internal energy. The quarkonium spectral functions and Euclidean correlators are sensitive to the interplay of bound states and the (non‐perturbative) continuum, and to heavy‐quark in‐medium single‐particle properties. Further applications in the heavy‐light quark and pure gauge sectors are addressed.