All purchased keys are valid for all versions of xVision.
Customers of xVision can download distribution archives here:
xVision 1.02 for using with X-Plane 11.21-11.26: xVision_102.zip
xVision 1.26 for using with X-Plane 11.30-11.35: xVision_126.zip
Please keep in mind that the further functionality of the tool is fully dependent on new X-Plane versions functionality.
One of significant part of xVision (shader tweaks) based on undocumented and unsupported X-Plane interface. Shaders are "bleeding edge" technology and may be changed by developers with next release of X-Plane in an arbitrary manner. Such changes may cause one or even all shader tweaks malfunction.https://developer.x-plane.com/2018/08/our-shaders-dont-like-to-be-touched/ may be useful for some details.
Please take this into account when considering purchasing/using xVision.