I blogged about issue this last year, and to my mind the question has not been resolved. Is being a member of the EU like being a member of a club, or like being in a partnership? If the former, then once you leave you are not obligated to pay for anything that the club has committed to pay for after you leave. If I leave a snooker club, for example, I have no obligation to contribute to the cost of a bunch of new snooker tables. That applies even if the club made the committment to pay for the snooker tables before I left. On the other hand, I can claim no share in the club’s property and assets.
However, if membership of the EU should be conceived of as more like a partnership, then I do have an obligation for to pay for anything that the partnership committed to before I left. But in that case I do have a claim on the partnership’s property and assets – -I’m entitled to my share of them.
The EU, it seems, treats the UK’s membership of the EU as like a partnership when it comes to discussions about the UK’s financial obligations, but like a club when it comes to discussing what the UK has a claim on (like the Galileo satellite system). The hopeless May government seems to be incapable of dealing with this duplicitous treatment.