Under EASA rules as said above you do not need to carry any personal logbook during flight operations. In fact authorities prefer you do not carry it as they can easier get to recency figures if it is somewhere safe in case of a crash.
That said, if you fly under in AOC operation you do not need to keep a logbook at all, the operator however is required to keep a detailed log not only for each aircraft but for each pilot as well and is required to hand them out on request of either the relevant authority or the pilot.
Still not a bad idea to keep your personal log, and logten is a perfectly fine way to do so. By synchronizing different devices you can keep several up to date copies backed up as well, for example i have it on both my ipad and iphone as well as on my macbook which in turns backs it up every hour to a timecapsule.