Need info about activating Hyper-V on a Windows 2012-R2

Hi Team,

I  have a windows 2012 R2 Standard Server. (It is licensed but i have no further information on it. )

I have the following roles installed 

1. DNS
   
2. HYPER-V
3. IIS

I have a windows 2012-R2 installed as a VM. 

I want to know how to activate it . What are my licensing option. Does my existing license involve VM licenses?

TIA