You must have a new license file to run AWR 2012 if you were previously running any earlier AWRDE versions.
If you try to use a license issued for a prior version, an error message displays.
If you view your license file with any text editor, you can see what version it is good for. See the bold sections that follow, first for a locked license:
INCREMENT MWO_228 awrd 9.5 31-dec-2010 uncounted \ VENDOR_STRING="E:Cust# xxx:ABCD CORP:AWR, \ Inc.:RP=1234" HOSTID=1234c12a12a0 PLATFORMS=i86_n ck=206 \
And for a floating license:
SERVER ReplaceWithServerName 1234567ac12c4 27007 DAEMON awrd FEATURE MWO_225 awrd 9.5 31-dec-2010 1 VENDOR_STRING="F:Cust# \
You need a license version of 9.5 to run AWR 2010. This license version also works with earlier versions back to v7.0.