Awesome product! One unobtrusive way to monetize is to simply allow users to store up to 10 shots (for example) for free, if they want more space they can pay something like $10 a month for up to 100 shots. The more space needed, the more they pay.
Also, providing an enterprise option might be a good idea as well.
What kind of things would you expect to see in an enterprise version?
Profiles for people to showcase their shots (sort of like Instagram has).
The ability to share shots with others.
The ability to have private scrapbooks that you can share with certain people.
Charge per month($50) plus per user($2)