Ok, I know that every obfuscated .Net application can be reverse engineered.
And I know that it is better if I go the open source way if possible. But u
Yes, one way to protect your IP is to hide parts of your application logic on a backend server where a cracker cannot simply remove simple piracy checks - they would need to reverse engineer your API to create their own service somewhere to keep the application working.
Note that while this makes things more difficult for crackers, it is not impossible to do, and there are several games who use this scheme that have successfully been "cracked".