just a heads up really I was caught out by this after I installed the upgrade
Prepar3d sees the upgrade to win 10 as a significant change to a new PC and the activation licence test fails if you have not uninstalled P3d first.
The stupid thing is I did not have p3d installed before the update, I was aware of the licence term and did an un-install first. my p3d was added after the win update using the correct licence details and it worked for several days before it failed
I contacted LM and to day they sent me confirmation of new licence details but I had no P3d for three days over