Adding a Souvenir Key Locker
This is a suggestion that could make money for Ingress.
When I travel, I pick up keys that have sentimental value but I will never use the key again. They take up valuable inventory space in the key lockers (which are usually full). Niantic could charge for a souvenir key locker that would allow you to save keys from trips that would never be used again. The difference between key lockers and the Souvenir locker is that you would be able to put the keys in the locker to keep and view but you can never take them out again, the only way to remove them is to delete them . The keys would not count against your inventory so you could have as many as you want.
Each Souvenir key locker could hold 100 or whatever (which Niantic could charge for).
I have so many keys that I just don't want to get rid of but will never use again and this would solve that problem.