Not bad
But: There should be a different Text configurable for different paid subscriptions.
From what I see here the same Text goes to all paid subscription Users.
Example:
Subscription1
Subscription2
Users which purchase Subscription1 should get a PM/EMAIL with TEXT1.
Users which purchase Subscription2 should get a PM/EMAIL with TEXT2.
(Subscription1 for example could be "purchase a key", this could be send via pm/email than)
If you get that to work, I will purchase the PRO version
Another great idea: For Paid Subscriptions you could create an option which gives the possibility to choose "One Time Payment" instead of the time range for a Subscription in the AdminCP. This would give your product a great Feature: One Time payments where Users receive only Informations in an Email

There isnt any Modification for this at the moment, I am sure many ppl will be intersted in that.
regards