We investigate spin-resolved decay of an axion-like particle (ALP) into an electron–positron pair in an intense laser field. Using the Baier–Katkov quasiclassical operator formalism in a constant crossed field, we derive a compact analytic rate retaining finite ALP-mass effects and the lepton spin degrees of freedom. In the massless limit, the spin-summed rate has the same weak- and strong-field asymptotic scalings as the corresponding photon-induced pair-creation rate, while the pseudoscalar coupling induces distinct spin-resolved channels and spin correlations. A finite ALP mass reorganizes the spectrum across the vacuum threshold, producing purely field-induced pair creation below threshold and spin-dependent oscillatory modulations above threshold through the coherent interplay of vacuum and field-assisted contributions. The entanglement of the produced pair reflects the dominant pair-creation mechanism. After the emission angles have been traced out, the reduced spin state near the vacuum threshold in weak fields is nearly maximally entangled and singlet-like. In the strong-field regime, it becomes triplet-like while retaining a concurrence approaching $1/2$, whereas deep in the vacuum-dominated above-threshold regime it becomes triplet-like and separable. These results establish spin-resolved spectra and entanglement as characteristic signatures of finite-mass and threshold effects in strong-field ALP decay.