Please use lowercase when posting forum messages - upper case is considered as screaming and also very difficult to read.
You purchased a 500 user single site CBSubs license back in 2010-04-06.
This initial purchase has a 1 year maintenance period included (allowing you to download and use new releases with your license for on year).
The maintenance period expired and you never renewed (you must have seen messages in your CBSubs backend about new releases).
In December 2012 we released the new CBSubs GPL 3.0 product:
www.joomlapolis.com/news/18335-cbsubs-30-goes-gpl-
We sent newsletters and personal mailings to all existing CBSubs purchasers with migration offers.
Please check your mailbox and spam folders for your messages.
You must have got them and they either ended up in your spam folder or you just ignored them.
CBSubs 1.0.3 is old and will not work on CB 1.9 (which is needed for Joomla 2.5/3.0).
So answer is that you need to upgrade your CB version to latest 1.9 in order to be able to use CB on Joomla 2.5/3.0.
You need to purchase a CBSubs GPL 3.0 membership in order to get access to CBSubs GPL 3.0 (contact us to see if we can extend the migration discount for you even at this late time).