Nero trial versions can be tested for 15 days starting from the date of installation.
AVC, MPEG-4, and AVCHD video formats are not supported for encoding in Nero trial versions. Also the burning options are limited (100 MB / 30 sec).
From Nero start screen you can directly buy the product. After purchase you can easily convert the trial version into a full version product.
To do so, just open Nero ControlCenter and enter the serial key delivered with your purchase.
Also check out the video tutorial
Nero KnowHow 00001