Just sharing my experience:
I have an old Win XP SP1 computer with Cubase SL3 and its dongle which works great (it´s noisy though).
I bought a fanless Win7 (with internet connection) on which I installed Cubase SL3 and Cubase Elements8.
I made a mistake and installed the license on the same old dongle. Now SL3 and Elements8 work on Win7, but the XP PC does not recognise the SL3 license. BUT it is solved now.
1- How to install cubase SL3 on a Win7 PC:
Install cubase SL3 from the disk oon the Win7 PC.
uninstall the old e-licenser
Download the last XP/Vista e-licenser
Connect old dongle (USB-licenser)
Open the e-licenser, it should see the SL3 license. Cubase SL3 now works on Win7.
2- How to have the old XP PC recognise (again) the SL3 license:
Get a new dongle (USB-licenser)
Connect both dongles (USB-licensers) to the Win7 PC
Launch the ´Wartung center’ (Service Centre I guess mine speaks German)
Transfer the Cubase elements8 license from the old dongle to the new one. On the old dongle should only remain the license(s) that were working with the old Win XP PC.
Now the old Cubase 3 dongle (USB-licenser) works AGAIN with the old Win XP PC and the new Win7 PC, the new Elements8 dongle (USB-licenser) works with the new PC.
3- Possible other solution (not tried):
The solution is to install the last XP/Vista e-licenser on the old Win XP PC. Unfortunately it needs SP3 and Microsoft NET framework:
SP3 is still availabe on the net (WindowsXP-KB936929-SP3-x86-ENU.exe) for english editions.
(SP2 also WindowsXP-KB835935-SP2-ENU.exe but i THINK you can go direct to SP3).
Microsoft NET framework is still availabe on the net Version 3.5 (dotnetfx35.exe).
Then, it would be necessary to uninstall the old e-licenser, and download and install the last XP/Vista e-licenser.
Now I have no intention to try: that old XP computer works VERY well and I do not want to take the slightest risk messing it up.