Every license has an expiration date and a maintenance period. A typical commercial license has unlimited expiration (you can use the product forever) and a maintenance period valid for one year.
If your license does not have unlimited expiration (for example because you have a trial license), you will not be able to use the product after the expiration date. If you want to continue using CloverDX (CloverETL), you can contact email@example.com and request an extension. When the request is processed, you have to download the extended license again and replace the original one with the extended one.
Valid maintenance entitles you to contact CloverCARE support with your questions and download new versions of CloverDX products. After the maintenance period is over, you will not be able to download new versions of CloverDX or contact CloverCARE support. However, the product itself will be still usable. If you want to renew your maintenance, just contact firstname.lastname@example.org. When the maintenance is renewed, you do not have to download the license again. Everything is done automatically in this case.