When you buy a new module, the license is valid one year (you can update the modules to the last version within one year).
After this period, you can renew the license which will be valid until the anniversary of the module purchase (1). If the license has not been renewed within 6 months, you will have to buy a new license.
Choose if you want to renew your licenses only once or if you prefer an automatic annual renewal (you can end it at any time):
(1) Example: if you buy a module on 06/23/2020 and renew the license after the anniversary date, for example on 07/18/2021, your license will be valid until 06/23/2022.