build vpn server

hi, i wanna start a new simple business buy selling vpn services

i have 2 servers one in USA and another in Germany

i have mobile application ready to connect to vpn

what i need is someone with provisional knowledge to Setup both servers to ready to serve vpn users
the vpn software must be scure and provide all protocols

also all servers must support for operations like register user, use user to login, set limit or plans for each user.. create packages.. etc