I asked Gobee via Facebook and I was told that the bikes can be returned to the banlieue proche (nearby suburbs). I asked for a map, but I got no response yet. I will try tonight to see if I can return it in Cachan and maybe later I also try other cities that I may visit around Paris then I give feedback.
Just locked one in downtown Cachan and it worked like a charm :-)
My impression about my first trip was fairly positive. During the trip there were no areas in the map that showed crosshashed, so I guess that the bikes can be dropped anywere in the Parisian region, which is an advantage over the Velib which is restricted to Paris and at most 1,5 km away from the city limits. Not necessarily you will be able to get a bike after you drop it in the middle of the suburbs since the one I dropped in Cachan never appeared in the map thereafter (someone got it quickly?). The bikes are light and the single speed is very low, which helps for uphill or for beginners, but in the flat or downhill for a fit male like me it is very slow. The saddle is just too low and can't be moved. The app seemed to be easy to use but the lock refused to move in the first try. I have to help the unlocking motor applying some force to the lock lever with my hand since the lock was stuck closed, but that was a simple fix. Yet using a smartphone to unlock the bike is not way as practical as using a contact card like the Velib. The bikes otherwise look in very decent condition since they are new, but I have to wait a few months to see if they are holding well after the winter. The Facebook chat was very responsive and the person in the other side appeared to be very well informed, but again the service is new now and probably I was serviced by a manager which must have very little work to do at this point. The price is a big downside over the Velib since it is paid after 1 minute while Velib is free for the first 30 minutes. If you find 5 minutes later that the bike is not good, you lost 0,5€ (unless the costumer service agrees to refund your balance, which still is a lot of trouble). I will keep using it since when I come back home there is no bus service in the evening and I had to walk 30 minutes from the closest Velib station to home while in the morning I take the bus and there are no plans in the foreseeable future to have a Velib station in Cachan (there are rumors, but none have a defined date). If this changes I will go back to Velib.
They also answered an e-mail that I sent before I contacted them via Facebook and I was informed that while they don't have a strict limit, they ask us to deliver the bikes within Paris or Lille metropolis or their "petite couronne" (nearby suburbs). This means that I could even pick a bike in Paris and return in Lille or the other way around :-). Still the second Gobee I returned Friday in Cachan was still sitting in the same spot Saturday afternoon and it did not show up in the map.