There are several ways to block license in a key remotely. However, none of them are both reliable and convenient.
Check serial number status (convenient, NOT reliable)
Guardant API has a serial number status check request. In fact it returns "yes" or "no". A serial number is an alphanumeric code that is generated in Guardant Station, and then is given to the client. The client uses it to activate the license (=install the software key) on the desired computer. You embed an API request call into your software, for example, once a day, as well as some interpretation of the response.
When you need to block a license, you will need to set the serial number status to "Blocked" in your Guardant Station personal account. Your software will detect this and, for example, delete the license.
This method in fact is a protection from an illiterate user. For a professional, it will not be difficult to "cut off" the status check. Of course, this case only works if there is Internet access.
Remove license (convenient, NOT reliable)
The logic is the same as in the previous version, only instead of the status, the software checks for license updates and automatically installs them on the PC using the Guardant Licensing API. To block a license, it is enough to create an update with outdated license conditions and/or with a dummy product. Pay attention to the "add-on mode" switch on the update creation form. If it is in the OFF position, then during the update installation on the user's PC, all previous licenses will be deleted. If the switch is in the ON position, the update contents will be combined with the existing products in the key.
Time limit (reliable)
When a license is issued to clients, its term is limited, for example, to one week. After this term, the license will be blocked. If there is a need to renew it, simply update the license in Guardant Station. If there is an Internet access, the procedure for updates checking and installing can be made completely automatic and invisible to the user.
