If you are interested in upgrading to the latest version with a perpetual license you can download the latest version of LR 5.6 at the link below. Mac or Windows version. You can run as a trial version for 30 days and then purchase an upgrade license for $79. You then activate the trial with the upgrade key and when prompted you can input the LR 2 original license key to complete the process.
If you still have your LR 2 Catalog file the LR 5 version will create an upgrade copy for use there.