I agree with everyone here that Object Desktop is definitely the best buy, and worth way more than the cost of a subscription. But to answer your specific question, this is from the WindowBlinds FAQ at Stardock.com:
What versions is my license valid for?
If you bought WindowBlinds on it's own you will be eligible for all updates until the next major version change. For example, if you bought WindowBlinds 3.0, you would be able to get WindowBlinds 3.3 now, and 3.4 in the future, but not 4.0 or later versions. For a limited time, WB 2.x users were able to upgrade to 3.x for a reduced price - this is likely to be repeated for current users if/when WB 4.x is released.
If you bought WindowBlinds as part of a subscription to the Object Desktop Network you will be entitled to all fully-released (non-beta) versions of WindowBlinds that fall within your registration period - if you registered a year ago, you would have had WB 2.2, and immediate access to 3.0 when it came out as well as versions through to 3.3, but would not be able to download any future versions unless you renewed.
Hope this helps clear things up for you.