Install 2N SmartCom (next just SmC) server. You will have 800 free hours for 2 users and 2 terminals. http://www.2n.cz/en/products/m2m/smartcom/downloads/

When you need to get a license, open a program in windows menu -> all programs -> 2N TELEKOMUNIKACE -> 2N SmC -> 2N SmC License Tool

Copy Server ID and CONTACT SUPPORT - https://www.2n.com/en_GB/support/technical-support

When you receive a license file, return back to SmC license tool. Browse your license and do an upload.

For checking whether the new license is saved alright, just close and open SmC license tool again. You will be able to see the new unlimited license for 10 users and 1000 terminals.