A couple days ago my Pi Toolbox v9.1 Pro install stopped working because the license expired. I tried contacting US support but received no response. The document I received when I purchased Pro said the following so I don't understand why it stopped working.
V9 also introduces annual maintenance. Annual maintenance entitles the customer to receive major version updates as and when they become available within the 12-month period. For example, a major is an upgrade from V9 to V10. A major release is planned to take place on an annual basis.
Annual maintenance will operate from January to January and is to be pro-rata from time of purchase. This is to ease admin and management of annual maintenance as all users will be aligned to January each year.
If a user does not take annual maintenance then they will only be entitled to minor updates. These are likely to be small improvements and bug fixes. For example, V9 to V9.1, V9.2 etc.
If a user has not taken annual maintenance for a number of years and would like to update to the latest major version of Toolbox then the annual maintenance is back-dated. For example, if they purchase V9 and over 3 years Toolbox has been developed to V12 they would be required to purchase the value of 3x annual maintenance fees.