How do I auto upgrade membership after paying?

How do I auto upgrade a membership after they have paid?

I haev tried a few plugin’s for generating membership (currently using wp-member) and the problem I have is they only create one membership level in WP… Whatever you have in your general settings as a start point (i.e. contributor) is what they begin as.

The problem is I want to have a trial membership that starts as a “member” role level and then after the same membership pays for monthly subscription, I want them to be upgraded to “subscriber” role level…

I have created the role levels without problems just have to manually go into users admin area and change them to new level…

Does anyone know of a php string (or) other code I could put into my theme files to control my membership levels?

I currently use:

<?php // add a private menu
if(current_user_can('contributor' || 'administrator' || 'editor' || 'subscriber')) : ?>

On a few theme pages I modified as to hide contact information from non members, this works great, only trial members can also see this information because everyone starts only as member…

I wonder if I could do some other type of “if” statement that made WP check to see if member has paid, if so then start as “subscriber” level…?