Can you keep the same IP when remoting into network?

Question

OK, so we have some software on the network that licences users by IP address. When a laptop is taken out of the office and uses a remote connection to dial in (either by using a RED or by Sophos SSL VPN client) they are obviously assigned a different address based on the pool assigned to that remote connection. 
 This requires two licences for the same laptop because it connects to the software server using two different IP's. 
 Is there a way to assign them the same IP as they get from inside the building without creating fundamental networking issues. Maybe spoofing the IP?

BAlfson · Answer

The RED is a separate issue and you may want to ask laptop users to come in via VPN when not in the office if you can't assign static IPs behind the RED. 
 With the VPN, you can use NAT, but I wouldn't try masquerading or 1:1. Instead, take advantage of the fact that "John (User Network)" is populated when user "John" connects via VPN and use an SNAT for each laptop as follows: 
 SNAT : John (User Network) -> {ports} -> {Host for server} : from {Host for John's laptop} 
 Cheers - Bob