Openvpn user management with mysql

We have OpenVpn installed. We want like this: User goes to our website, pays/signups He gets redirected to a page where it will show his login info for VPN. Meanwhile his user and pass is automatically created. If it can be done with mysql is good if not by other means like a file with user/pass combination into wich php writes on user creation. But also like we can let them buy like a trial for 2 days and after 2 days they cant login. Or something that we can check by if they have an active subscription or so. Maybe its easier with mysql if it can be done. Basically a mysql user management, wich allows us to set like trials access, etc. Thanks