You’ll probably need to make an animation event in the last keyframe. Then you can use :GetMarkerReachedSignal(). It returns an event (RBXScriptSignal) that you can use to run a function when the keyframe containing the animation event is reached. In the function you connect to it, do animTrack:AdjustSpeed(0) to freeze the animation to its last pose.
I’m not sure if that is enough. If it doesn’t work, then also add an extra keyframe to the animation to make sure that it is still playing when it’s paused.