Pro Sites + Pay to Blog doesn't lock site

I have just started creating my environment for my first commercial network.

Here is the flow I would like to recreate:
- The site is created with Gravity Forms - not default registration - each site is immediately granted 30 days free trial
- During the 30 days free trial the user has the option to go PREMIUM at any time
- After 30 days the site is locked (both front and back) and the user is only redirected to the payment from.

So far I have my first issue - the "Pay to blog" module from PRO SITES does not lock the site.

Here is a sample site:
https://michallew.xpresso.pl/

I have removed the Pro sites status manually - in the history of the site it states "Pro Site status has been withdrawn". The site status is marked as "Expired Pro Site".

The user has the backend locked (is redirected to payment) but the front end still works - both for logged in user and for anonymous visitors.

Please help.

P.S. Ignore the SSL warning - I'm waiting for my certificate to be issued.