Mysql Add user to Paid Subscription

[datarecall]

I have a store and if someone purchases from my store I want to add them to the paid subscriptions usergroup for x amount of days I found the subscription log and tried inserting the information into there however that did not update their account.

To go in manually takes way to long so I was looking for a way to streamline this. is there a table I am missing or a vbulletin script that can help with this ?

$insert_array = array('subscriptionid' => 1,
'userid' => 128003,
'pusergroupid' => 52,
'status' => 1,
'regdate' => strtotime('now'),
'expirydate' => strtotime('+2 months'));
$sql2->insert($insert_array,'subscriptionlog');

any help is appreciated.