Let G be a connected and simply connected Banach-Lie group or, more generally, a BCH-Lie group. On the complex enveloping algebra U C (g) of its Lie algebra g we define the concept of an analytic functional and show that every positive analytic functional λ is integrable in the sense that it is of the form λ(D) = dπ(D)v, v for an analytic vector v of a unitary representation of G. On the way to this result we derive criteria for the integrability of * -representations of infinite dimensional Lie algebras of unbounded operators to unitary group representations.For the matrix coefficient π v,v (g) = π(g)v, v of a vector v in a unitary representation of an analytic Fréchet-Lie group G we show that v is an analytic vector if and only if π v,v is analytic in an identity neighborhood. Combining this insight with the results on positive analytic functionals, we derive that every local positive definite analytic function on a 1-connected Fréchet-BCH-Lie group G extends to a global analytic function.