The standard license that is purchased is a perpetual use license. This means, it is a once purchased license that guarantees continued use of the j2 software in perpetuity subject to the terms of the j2 EULA. Once a perpetual license is purchased, the user can ask for the license to be transferred to other machines provided the j2 software has remained in support under the terms of the j2 user Software support and maintenance agreement. This is purchased annually or multi year and the maintenance and support is charged for after the first anniversary of the purchase has lapsed.
Any users who do not purchase the software maintenance and support after the first year may need to repurchase a new license should their machine malfunction or they move to a new operating system within the company. If the product is in support j2 will issue a new license free of charge provided the terms of the EULA are met.
More details can be found by reading the EULA or by contacting j2 directly.