Hello Stefano,
Thanks for the quick response!
When we create an Entitlement we get ENTId(integer) as an response.
To know EID(string) of any specific ENTId(integer), "Get Entitlement Using Entitlement Id" Web-service can be used.
In order to get the EID as an output we just need to input the ENTId of an entitlement.
Hope this helps.Feel free to get back to us in case of any concern.
Regards,
Ashish Kumar