can't reactivate Traktor Pro Plus in Traktor 3
I expect that contacting support won't be of much use in that case. Traktor Pro Plus subscription is no longer offered. The features unlocked by that subscription are now part of Traktor Pro 4 without subscription.
Therefore I expect that this behaviour is intended by NI.
You need to contact N.I. Account Support .
Please refer to the page : How to get in touch with our Customer Care