That's the thing about the activation code...I don't think you can keep using this version forever as at some point you will presumably upgrade your PC and the software will ask for a new activation code. If they're not handing them out for free anymore, you're out of luck.
Yes, Farnell did acquire Eagle but it didn't become free. Again, I can't see Allied getting all THAT much business from its DesignSpark integration that it can afford to subsidize the maintenance and development of this program forever. But that's just bar sport speculation of course 
I also like the "openness" of Eagle with respect to being able to export libraries, use script files to create parts, ULP language, etc. The user is in control of their data in this way without the software actually being open source. I didn't see such an openness in DesignSpark.