Software’s lifetime access means that you will have access to my services and all upgrades or new features of the software for the current software's entire life. This is not applying to future software or add-ons embedded in current software in the future.
As stated above, you will never be asked to pay other fees, except for new software or new add-ons.
Both of us will assume a risk:
I will assure you services for a long period of time (database update, new features, upgrades..etc.), without other payments from you. The software has been working for 10 years already, and I hope that more will follow.
You understand that the services can stop anytime due to conditions completely out of my control or will, for example, a new version of Windows incompatibility, my incapacity to assure the services and other similar events. In these cases, you will not ask for a refund for your “software’s lifetime” subscription because the software’s life is finished.
If you understand my conditions, you could apply for a “software’s lifetime” subscription.