DJI has removed some servers which the older versions of DJI Assistant 2 relied on. That is why we have decided to suspend the sale of NLD Client keys until we have a workaround the issue. Based on our previous experience on our not so accurate attempt on estimating a release date we will a wait a little while before announcing the release date.
UPDATE:
We are have a solution and are working on a implementation and we expect to have something ready for you within 2-3 days.