I have developed a linux desktop application which has a variable cost depending on how many "widgets" the user intends to create with my software. If they exceed that amount they need to purchase access to create more widgets.
This all has to be done offline as the widgets are highly confidential and the customers tend to close off their networks to the outside world.
I plan on providing the customer an encrypted license key which will embed usage info regarding how many widgets they have purchased.
The problem I still have is how to keep a tally of the number of widgets created as they are created. And how do I make that tally tamper proof.
What I don't want to happen is to save the number of created widgets to a file and then when the customer hits their purchased limit they just set the file back to an older state and continue creating widgets.
Any ideas for offline, tamper-proof usage tracking? My desktop app currently only targets linux.
An on premise license server would be alright but not sure how to protect against database tampering?
I have seen many professional license solutions that make use of such as the ones by Sentinel Hasp (https://sentinel.gemalto.com/software-monetization/sentinel-hl/)
They have several models that are standalone and don't even require network access of any kind.
They may have a model that has a built-in memory or a register location that you can write uses to?