Please note that Bitnami installers based on open-source applications (like TestLink) are free of charge. Therefore, there isn't any trial period and you can use it for as long as you want.
Also, note that there are several platforms for running the stack:
- Installers (for Windows, Linux and OS X).
- Virtual machine images (for VMWare and VirtualBox).
- Cloud images (for clouds like AWS, Google Cloud Platform, etc.).
From your message, it seems you want to download and install the TestLink installer, so it does not use any cloud service.
Let us know if you have any other question.