My scenario is pretty simple. I own a desktop PC and a Laptop, both running Windows XP and Windows 7 in a dual-boot environment. Let's say I want to have Adobe Photoshop on both machines, all four boots, how many licenses do I have to purchase?
Hi, you can install Photoshop CS5 on as many computers as you want, but it can only be activated on up to two instances at a time.
So if you had a single license, you would have to choose which boots you'd want Photoshop running on, and then move the activation between them, if that worked for you.
With two licenses, you could activate and run it on all four boot instances at once, no problem... You wouldn't have to continually switch or change the activations between systems.
This is an improvement in flexibility on how it used to be - until recently, Adobe had a limit on how many cumulative reactivations you could perform with your software license.
If you are going to buy more than one license, you might want to take a look at Adobe Volume Licensing, which gives a price discount plus the ability to run a single copy of the software with a single serial number on all machines and platforms (Windows and/or Mac) that you own, and expand if you need to.
Hope this helps!