I suggest that your license management should be changed in order to accept the addition of licenses durations like Bitdefender does ?
for instance: I have Freedome running with 61 days license remaining, I purchased a 1 year license with 30% promo thanks to a mail offer from F-Secure, the problem is you can't add a new license to an existing one. Thanks to Ben I received a redeem voucher to compensate for this. That would be a lot easier to allow addition of durations.
BTW thank you for your products quality and the kind responsiveness of Ben.