here's the logic
after the users register, your system must have a function to approve or reject the users.
this might be useful if you have stored it on database like a column for `isApprove` that contains 1 or 0
now its your choice how you design it but in my case i did it that the isApprove column has the default value of 0
if isApprove is equal to 0 then the user is still pending and waiting for the admins approval
if isApprove is equal to 1 then the user is approved by the admin of the system