In my project the key is generated using MAC address primtive and mixed with a string (the root).
So, by that way, a valid code should be generated for any computer in use. The validation of a key, can be done with an osm (a standalone app).
The user have to save an autentication file (or text key) generated from the pc in use, then open the validated serial number.
If validation is not present on the disk (the key file) the plugin continues to show the activation popup and no sound come from the synth.

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the panel is not completed for nowAny time the synth or effect is loaded, the activation key on the disk is compared with the mac adress in use in that system.
The key algorigthm can be also automated via php but i'm not good as necessary to perform that code (also if is not complex).
In fact, the algorithm uses "hex to string" "string to hex" "string length" "integer data" and "integer operations + - and *), also portable to php. ( i think any programming language )