1. IDM lifetime license.
IDM Lifetime license purchase is one-time payment. There are no any additional annual fees. The license will be valid for lifetime. It means it will never expire.
2. IDM one-year license.
This license expires in one year after purchasing IDM. It means that IDM stops working and asks to enter a new product key in one year unless the license is paid and extended for another year. In general this license is one-time payment as well, unless you decide to make it a subscription during purchase process.
Please note that IDM has per computer license. In order to use IDM on several computers at the same time please obtain separate licenses for each computer.
You can however use IDM on several operating systems installed on the same computer or for multiple user accounts under the same operating system.
You can use the same license after system reinstall, but if you often reinstall your system on the same computer, please download and install the latest version of IDM.
It has additional binding to the hardware and will not block your serial number if you use it on the same computer. Also it is always better to use the same computer name after each reinstall.
If you want to move IDM on another computer, you need to uninstall IDM from your old computer first if it is possible. If the old computer is broken, stolen or formatted and thus IDM will not be used on it anymore, it is also OK. Then you may install and register IDM on a new computer.
Trial version works for 30 days only and then requires serial number.
Registered version works for your lifetime and has a number of additional features: no usage limitations, better utilization of bandwidth, built-in download logic optimizer.