A e-mail from IPS

[Micro]

As long as you downloaded 1.3 or 1.3.1 before the paid versions of 2 were released then you can legally use them.

 

[dest581]

And, just a note to clear up possible confusion, starting with the latest version of IPB, ipscheck won't work. They will run the system like vBulletin does.

Just a heads up.