Windows Server 2012 RDP issue

Hi I have a windows server 2012, which runs TSPlus software to publish applications. Problem: There are two servers, server A and B. Both Windows 2012 servers. Server A has TS Plus installed and it is able to publish applications (similar to Citrix App Publishing) for 20+ simultaneous users. Server B has TS Plus installed but it only able support 2 simultaneous users. Upon further troubleshooting, it is found that Server B does not allow more than 2 remote sessions. For server A, when we do mstsc /v:serverA, it is able to open up remote sessions for more than 2 users, but for Serv B, when we do mstsc /v:serverB, it cannot open remote session for third user, when it reaches 2 users limit. Because of this when more than 2 users are opening the remote application, server B cannot support. When we checked with the ServerB hosting vendor, they informed us that we need to buy CAL for Windows Server to overcome this limit of 2 users. We did not buy any CAL for Server A, but it is working fine. I need some windows server expert to check both Server A and Server B and see what is the difference. And provide a solution to fix this problem. If you are familiar with TSPlus, it will be helpful