Just purchased QT Pro, but will not accept registration number, help....

Just purchased QT Pro licence, but my 10.9 OS will not accept registration number, help....

Are you following THESE instructions? Did you enter (or copy) both the NAME and REGISTRATION KEY exactly as contained in your email. Did you press the TAB KEY to register the entered information?

Yes I've copied and tabbed, but nothing at all happens other than the tab highlighting first the Name then Organisation and then Reg code sequentially....

So you are not getting the word "PRO" superimposed over the QT 7 icon nor the phrase "QuickTime 7 Pro" beneath the Registration code: entry box but you are also not getting a message stating the key is invalid? If true, it sounds like there is either a problem with the QT OS v10.9 installation, the QT 7 v7.6.6 player app installation, or the file to which the key information is supposed to be stored is not being re-written/updated since the key appears to be neither recognized nor invalidated.

In the free version of QuickTime Player 7 the word "Pro" is shown in every menu option that requires the upgrade.

Open QuickTime Player 7 and look at all the menus. Do you see that the word Pro is gone?

When I go back to QT player, the Pro version is nowhere to be seen.

The only difference you should see is:

1) The "About..." window should contain the "QT 7 Pro" icon as seen below...

and

2) Some additional menu options may be available. However, since the QT 7 Pro app is context adaptive, you must load a file into a player window before these options become available. For instance, without a video loaded, my "Window" menu looks like this:

You will note that the "Show Movie Properties" window is unavailable because no file is loaded and, therefore, there are no file properties to be displayed. The same is true for the editing features if no video has been loaded to the app which can be edited. But, if I load a video, then this is what I see:

In addition, even with a file loaded, some options of functions may not be available if they do not apply to the particular file that is loaded. For instance, you can't set frame level "in" and "out" points for a muxed MPEG-2 long-GOP file because QT 7 knows the difference between frame-level files (which can be edited by QT 7 correctly) and long-GOP files (which it cannot edit correctly). Basically, QT 7 Pro can tell the difference between playback-compatible, conversion-compatible, and edit-/fully-compatible files when it opens them and will only turn on/allow you to access those features and options that can be used with the type of file you have loaded into the player.

So now the question becomes one of whether or not the app is actually keyed for "pro" use and you were expecting visual changes to the look of the QT 7 "Pro" app which do not, in fact, exist, or if you simply did not understand the context adaptive nature of the app and how it works.

Went back to it a couple of hours later.... QT Pro has disappeared and so has QT 7. In it's place is a simple non upgradeable QT Player.

I've no idea what's going on.... any thoughts?

Where are you looking for the QT 7/QT 7 Pro player? (I hope you did not move it from its installation location or accidentally delete it.)