Hello,   1. The OS10 license is permanent.   2. I'd have to refer you to the Sales department for anything pertaining to pricing. Pricing information isn't something tech support sees.   3. As for OS10, Enterprise edition is the edition Dell maintains, whereas the Open edition is open source and maintained by the public foundation. I can try to find any other differences, but the big one seems to be the maintainer.
It's hard to find clear cut answers. 1. Is OS10 enterprise license permanent? 2. Does pricing depend on the device model? (If not purchased together with the device) 3. What are the fundamental differences between OS10 enterprise and OS10 open edition? (probably no VLT in open edition?)  
OS10 licensing logic?