how to change licence key

[sysme]

You have to purchase a new license in https://www.sysme.net/tpv/sysme-tpv and if you want to keep existing data also purchase a 1 hour support service: https://www.sysme.net/tpv/bono-soporte-software-sysme

And remember that the new license will be valid just for 1 pc and company .. otherwise will be deactivated.