This is the procedure that I use to give Windows servers in AWS VPC a static IP address.
The first step create a security group that allows RDP and ping from my address
Go into the VPC dashboard navigate to Security Groups and click on Create Security Group.
Edit the security group by clicking edit.
Create rules allowing RDP and Ping to come from your source address.
to limit it to one IP address use 184.108.40.206/32. The slash 32 limits incoming traffic to that exact address.
Create a Network interface and assign it a static IP address.
From the EC2 Console go to Network interfaces and Click Create Network interface
Add a description, make sure it is in the correct subnet, assign an IP address (the first few are reserved so I like to start at 10), Click on the security group created earlier and click Yes, Create.
Create a Windows instance in the correct VPC subnet and assign it to the Security group created previously.While the instance is building attach the network interface.
Go into VPC Dashboard > Elastic IP’s and allocate a new address
Then click yes to allocate the address
Right click on the new public address and click associate
Choose Network interface to associate with and choose the network interface that corresponds to the static interface created earlier. And click yes associate.
Log on to the windows instance and disable the Ethernet adapter that has the dynamic ip address.
After this the server will only have one statically assigned IP address