EXP/Level system with and ingame currency for an open source github project.

Hello, so i would like a Level/EXP system with a register/login option that includes an ingame currency which the player can use to buy certain ingame items with. This is the github source that i would like it to be made for. *NOTE i didnt make the project [login to view URL] The project is basically a clone of the game [login to view URL] In the game the player is a cell, which has to eat as much as possible to be able to grow in size. The player can eat small cells that spawn around, or other players, each cell/player has a certain amount of mass, players usually spawn with 500 mass. I would like players to get 0.5 EXP for every 1 mass they eat, so if they would eat a player with 500 mass, they would get 250 EXP. And to get to level 1 they would need 500 xp, and to get to level 2 they would need 1000 xp, and level 3 would be 2000, and level 4 would be 4000 and so on....