Each TechNet Standard product key is good for one activation, although you can use the normal Microsoft channels -- online and telephone -- to reactivate a copy on the same machine you installed it on originally.
Is there a catch with TechNet, too? Of course ... what fun would it be if there wasn't?
Technically, you're not allowed to use the software you obtain via a TechNet subscription if you let it lapse. If your sub ends, "You must stop using the software ... and you must destroy all copies of the software in your possession," Microsoft says in the subscription agreement.
Other licensing language spells out additional legal restrictions.
"You may not use it in a live operating environment, a staging or production environment, or with data that has not been sufficiently backed up," reads a help document on the TechNet site. "You may not use the evaluation software for software development or in an application development environment."
On the plus side, a TechNet Standard subscription also lets you download and install other Microsoft operating systems and programs, including Windows 7, Office 2010, Office for Mac 2011 Home and Business, and when it ships, Office 2013. The two-keys-each rule applies for those as well.
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