When you try to activate your third computer you will be prompted to deactivate all computers. Once you have done that you can reactivate on that current computer and the other computer you are using Creative Cloud with.
Jeff summed it up well, and just to expand further... Generally, you are allowed to install and activate CC on up to two computers. If/when you put it on a third, you'll get the screen below (which looks like something failed) – but just hit "Continue" at the bottom of the dialog box, and it will do what Jeff said.
If you run into any issues, then see this help page:
Is it possible to deactivate a specific computer - in this case I have CC on my Macbook Pro and Windows workstation in my studio. I want to install and activate in Nepal on a Mac. When I want to activate - will I get the chance to select which computer to deactivate?
No Gary. Instead you will be prompted to activate on the previously activated computers. This allows you to decide which previously activated computer you wish to complete the activation sequence with.
So Jeff, one key difference in CC then: With CS6, you could choose to deactivate a specific computer from the Help menu – but with CC you can't do that, signing out via the Help menu isn't enough to deactivate that installation... is that right?
ProDesignTools you can sign out or remove all installed Adobe Creative software titles to also deactivate the software.
With the activation method though available for subscriptions it is easier to reactivate on the computers you wish to continue working on once you have chosen the deactivate all option.
More details regarding the activation process, and how to deactivate and reactivate depending on the version of Adobe software, at Activation & deactivation help - http://helpx.adobe.com/x-productkb/policy-pricing/activation-deactivation-products.html.
OK good. So there isn't such a difference between the two versions really, is what you're saying... Signing out a Creative Cloud application (from the Help menu or via the CC Desktop App) will also deactivate it.
So it sounds like what Gary could also do (as an alternative), is first sign out on the specific computer he wants to deactivate before he tries to reactivate the software on a different (third) system... Then he wouldn't ever get the "activations exceeded" screen that would forcibly deactivate both original machines when "Continue" is selected.
Finally, another important note from the helpx link you posted: When uninstalling programs, you always want to sign out of them first because uninstalling the application from a computer does not deactivate it.
This is all good to confirm so we can update our guide on how to move Adobe software between computers.
One final question for you Jeff: Presumably Adobe keeps track of how many complete "activation resets" happen for a CC membership... will customers ever run into difficulties if they do this only occasionally?
They really shouldn't. Unlike the previous activation method where the activation was tied to a specific computer, with the new activation method you are allowed to activate on a specific number of computers. As discussed if you choose the deactivate all option you will then need to reactivate on the previously activated computer. There should be no need to contact our support team and request an activation reset as might be needed for the perpetual products.
Thanks Jeff and ProDesignTools. Initially on the CC app the sign out tab was greyed out. After an hour or so it became visible and active. On Tuesday next week before my flight I will deactivate the windows 7 workstation and when I arrive in Nepal I'll set up and activate the CC acount. I would rather not have to install and uninstall - this seems to be the best solution. Just wish I didn't get those pesky - complete your registration screens and trial screens coming with the software.