Bart / Rolf,
This change stemmed from an issue that was present in ArcPad 8 and previous versions. On occasion, if an administrator installed and registered ArcPad, when a non-admin user then logged in and tried to launch ArcPad it would prompt them for the registration code again.
To get around this issue the location of the registration number was changed from HKEY_LOCAL_MACHINE to HKEY_CURRENT_USER. However, we are well aware that this has caused just as much trouble for our customers as the bug that the changed stemmed from.
Because of this we are working to get the location of the registration number changed (and the admin issue resolved) so that the ArcPad registration number only needs to be entered once on a machine.
There isn't a verified fix yet, but one will be included in a future release.
Feel free to respond if you have any additional questions.