As a non profit organisation, we can buy windows server essentials for 50€.
It says: Windows Server Essentials is an edition of the Windows Server operating system designed for small organizations with up to 25 users and 50 devices. When installed on a server computer, it automatically configures network roles such as print server, domain controller, web server, and file server.
Do we also need Windows Remote Desktop Services Device CAL for every SAMBAPOS user (10€/user)?
Any experience with this setup??
FYI: We only use SAMBAPOS 2 times/year… and have 8 users… so the extra RDP-licences would be an unexpected cut of our benefit-profit 
You don’t offer enough info.
What are you expecting to use RDP for?
Sambapos 4/5 will run on versions of Windows 7 upwards.
You do not especially need server edition windows for server.
Multi terminal just connects to a centeral MS SQL.
Typically the only use of RDP would be to use non Windows tablets for table service devices.
We currently use v5 with 3ipad & 2 android tablets. We use these patch, but thinking migrating to Windows server. So we need RDP. Hoping that is included with server essential version.
Multi RDP would unlikely be inclusive, although I am not familier with the package you refer to. It is usually through way of additional licences.
My personal alternative to an RDP server for non Windows tablets is additional mini/SFF PCs for the tablet so RDP to.
Alternativly the android app for samba is curently in beta or you could look to try out the PMPOS which is web based app using the samba API.