Yes, you can.
When testing on a local, non-public site, you can even activate the add-on without it counting towards the activation limit. Make sure that you simply need to run your plugin on a URL that matches to one of these properties:
If you are running the plugin on one of those URLs then it simply works.
You can always manage your activations in your account. In case our license system can not determine your site as non-public, you can just deactivate the license on your test environment to use it on your live site after testing. There should be a button for this behind the activated license key.
If you need multiple activated licenses then please check out the large discounts we offer for larger volumes of license keys.