Can I install my Windows 7 once on my "normal" desktop PC and then later, after months, on my laptop again, so twice?
or is not that possible because of the key?
(at least I could have bought myself a new computer, for example)
Can I install my Windows 7 once on my "normal" desktop PC and then later, after months, […]
Yes, it is not allowed by license. Although you can transfer existing licenses to new devices, you can't use them in parallel on other computers.
Of that time, on the Internet quite cheap Windows licenses can purchase. Currently on MMOGA Windows 7 Professional for 7.99 euro is offered for sale.
https://www.mmoga.de/Software/Windows/Windows-7-Professional-32-64-Bit.html
As the support end of Windows 7 is approaching, thinking about switching to Windows 10 anyway. If it is software-technically possible, maybe even move to a free Linux derivative and Windows only temporarily used as a virtual machine.
You can install the same version of Windows on so many computers you want. Only you have to have your own suitable license for each installation (unless you have a license that includes multiple installations)
I do not know how it is today, with the same program key on two systems at the same time. - Bill Gates is said to have said some time ago, he prefers a key to be used multiple times than a computer system is completely unprotected or hacked (that's what I have in mind).
It is not correct to use the same program key on two systems. At least not if you sell your PC and still use the key for your Lappy. So if one of the computers is no longer your property.
