Not exactly directly cloud related but a work around for some of the hurdles Microsoft place around using legitimate licenses.
If you have a valid Windows 10 Pro license from any system, for example an old laptop or perhaps an OEM key bought from a reseller which you are only using on a single device, you can run into all sorts of issues try to apply it to an existing Windows 10 Home system.

Errors

Errors while attempting to change the activation key include:

• 0xC004F050: The product key you entered didn’t work
• 0x803fa067: We can’t activate Windows on this device because you don’t have a valid digital license or product key.

Contacting Microsoft support I was given the suggestion of going to the Windows Store app to purchase a new key.  This was doubly annoying because not only did I already have a valid key but the suggestion simply didn’t work.  I could browse the store and find Windows 10 Pro but clicking the “Learn More” button (where I assume you are given some pertinent information like the price and an opportunity to purchase) resulted in a blank page.  An hour of online chat and remote troubleshooting resulted in a reboot which lost the remote session.  A disappointing experience to say the least.

Workaround

Eventually I ended up using a two phased approach.

1. Upgrade

First upgrade the system to Windows 10 Pro using the generic license key published by Microsoft some years ago. 

• VK7JG-NPHTM-C97JM-9MPGT-3V66T

This is perfectly legal, it does not activate the system, just upgrades it, however, in order to make this work I had to disconnect from the internet (turned off wi-fi and unplugged my ethernet cable).

2. Activate

Once the upgrade process was complete I reconnected to the internet and attempted activation.  It failed.  I then used the telephone activation system which sent a link to my phone.  I used this to enter the Activation ID into a web form.  During the process you will be asked how many computers you have installed the software on.  Don’t make the mistake I did and reply 1 – respond with 0.  You are then presented with a confirmation code to enter into the activation dialog on the upgraded system.  This should complete the process and activate Windows 10 Pro.

Note:  this post is not suggesting using invalid or illegal keys, it is meant to enable using valid keys which have been incorrectly prevented from working.