Chanalyzer is licensed per user, not per machine. This means that you can install it on several machines for one user. For example, you might want to use Chanalyzer to record in the field on your laptop, but use your desktop to build out reports.
Multiple machines that belong to you personally? Install it on up to 5 of them.
Multiple users? Get them each their own license.
You can activate the key 5 times.
No Available Activations
"I'm getting the error 'No available activations for this product key'. What do I do?"
The key was probably activated 5 times already. If you need to clear out old activations, create an account or login to your my.metageek account, and visit the Licenses page.