After installing Emacs BBDB from Melpa on GNU Emacs 24.3.1 (i386-mingw-nt6.1.7601) for Windows, if I run M-x bbdb-version I get:
BBDB version @PACKAGE_VERSION@ (@PACKAGE_DATE@)
How can I know if I am using the new version 3 of BBDB?
This is a known issue, the author uses a build system to define and replace these names with their correct values, but melpa does not support making changes to the upsteam repo.
The truth is, if you just downloaded it from melpa, then it is safe to say you are running version > 3. If you really want to be sure, do C-hfbbdb-with-print-loadably and see if that function is defined, it was added to bbdb in one of the most recent commits to the git repo and well past the last release commit of version 3.1.2.