Licensing only applies to SSMS 2012 and higher versions.
For previous SSMS versions the SSMS Tools Pack is still FREE
After a valid purchase a confirmation email with the License Activation Key will be sent
to the email address you used in your PayPal payment process.
A license is valid indefinitely for the major (2.x, 3.x, ...) version you purchased it for.
That same license is also valid for one year from date of purchase for any other major version.
See all licensing details in End-user license agreement (EULA)
Really, there is interesting stuff in there :)
License Upgrade has lower cost than buying a completely new version and can only be done
from the immediate previous major version. You can upgrade from 2.x to 3.x or from 3.x to 4.x but
not from 2.x to 4.x. Going from 2.x to 4.x requires a purchase of a full new version.
Unlimited VMs mean that you can activate the SSMS Tools Pack on any number of Parallels, Hyper-V, VMWare, Xen or VirtualBox Virtual Machines.
Since successfull detection depends on many factors the VM check can return both false positives and false negatives in about 0.1% of cases.
Please let me know if that happens.