As no one has answered I will try as best as I can, even though I don´t know the whole story.
You can change the serial and MAC adresses of you xpenology when making your boot device. It has been mentioned in other posts that, MAC and serial addresses are sent to synology when activating licenses and tie to those. Whether using a DS-411slim serial how/if this changes the behaviour of you device - someone else might know. I haven´t tried this.
There is though a way you can make surveillance station accept licenses without online activation. With this method you don´t have to change serial / mac address. This loophole might be closed at some point though.
This way there is no online check, and it should accept your official bought license key(s). The key still needs to be valid and not blacklisted.