I have a package that is developed in SSIS 2012 using Visual Studio 2010.
Is it possible to deploy/attach this package on SQL Server 2008
If it is possible, does the licence of the sql server matter
no, you cant. SSIS package are not backwards compatible.
Also it doesn't make much sense if you think about it. If it was the other way around, "maybe" it could be done because 2012 would somehow be aware of 2008 structure, but 2008 engine isn't aware of 2012 package structure.