Astrill application is a Plug-and-Play VPN client software bundled with a lot of unique features not available in any other competitor service.
— There is no version regarding the trial version of the software and its period.
I have contacted Live Sales and the person from the team said that you have the possibility to test the service for 7 days. You need to use the Sign Up page to select the 7 Days trial option then fill the details. You can check the image bellow with the conversation.