Every time I load the aircraft  I am asked to activate it, which I do,  and activation is acknowledged,

 Windows 7 FSX, have reinstalled 3/4 times , then PMDG Operation Centre updates carried out,

but frustrating issue persists.

Michael King

2 hours ago, MAHLER said:

Every time I load the aircraft  I am asked to activate it, which I do,  and activation is acknowledged,

 Windows 7 FSX, have reinstalled 3/4 times , then PMDG Operation Centre updates carried out,

but frustrating issue persists.

Michael King

I recommend you contact PMDG Product Support (this is a user forum, not much we can offer for activation issues). Stop reinstalling, that isn't fixing your problem.