The pricing model for CloudBacko is Perpetual, meaning you buy and own the current version software. That means it's a one-time payment. The pricing includes software maintenance for the current version that covers Ticket Support and Software Update within this version.
When next version released and you want to upgrade, then the upgrade fee will be 40% of the list price of all your software and modules. But if you don't upgrade, you can still use the version that you bought without any problem.