I've installed Viewranger on my Motorola phone and it works fine (so far!) However, I downloaded two OS tiles (free samples) which also work well but I wish I'd have downloaded different ones. I seem to recall reading that you can 'surrender' tiles and load different ones instead. Is that right? If so, how? I can unload the tiles from my phone but can only load those two back on, no others.
Second question is that if I buy a set of tiles, do they last forever or do I have to pay yearly to keep them?