You could make it a location based service, and prices increase as the number of users in the area increases. This incentivizes people to sign up when there's not a lot of active users in your area because it's cheap/free. Then as more people in an area sign up, new users pay more to reflect the added value of the app.
You could make it a location based service, and prices increase as the number of users in the area increases. This incentivizes people to sign up when there's not a lot of active users in your area because it's cheap/free. Then as more people in an area sign up, new users pay more to reflect the added value of the app.