Recently while working in my lab I wanted to force the address book to update with the Lync 2013 client. This is a fairly straight forward process as all you have to do is import a registry key (or wait randomized time between 1-60 mins which is the default). After importing the key and found that the Address Book still wasn’t downloading. Through troubleshooting I found the issue was that my OS was x64 and my Lync client was x86. I completely overlooked this so I figured I would give everyone the keys that I used so you don’t have to research if you run into this. The location has also changed from Lync 2010 to 2013.
Lync 2013 and OS same bitness (both either x86 or x64)
reg add HKLM\Software\Policies\Microsoft\Office\15.0\Lync /v GalDownloadInitialDelay /t REG_DWORD /d 0 /f
reg add HKCU\Software\Policies\Microsoft\Office\15.0\Lync /v GalDownloadInitialDelay /t REG_DWORD /d 0 /f
Lync 2013 Client and OS different bitness (combination of x86 and x64)
reg add HKLM\Software\Wow6432Node\Policies\Microsoft\Office\15.0\Lync /v GalDownloadInitialDelay /t REG_DWORD /d 0 /f
reg add HKCU\Software\Wow6432Node\Policies\Microsoft\Office\15.0\Lync /v GalDownloadInitialDelay /t REG_DWORD /d 0 /f
After adding these keys you must exit and re-enter the Lync client. You can check for the address book files in %userprofile%\AppData\Local\Microsoft\Office\15.0\Lync\email@example.com. You should now see two files named galcontacts.db and galcontacts.db.idx.