Locklizard Instructions & Frequently Asked Questions

Some downloads sold by The Masonry Society are protected by Locklizard DRM and can only be opened using the Locklizard Viewer software. Protected products are clearly noted on the store page and can also be identified by a SKU beginning with LLF. These products are provided as .PDC files, which cannot be opened using any other PDF software.

These files provide single-user access only. Click here for multi-user options

Download Your Files and License

Your files and Locklizard license can be downloaded from the Downloads and Document License tabs on your Account Page.

Frequently Asked Questions

Can I print from a .PDC document?
Most TMS publications provide limited printing. These files can be printed from up to 2 times. Some files (e.g. Masonry Structures, Masonry Course Notes, and Plan Set) do not allow any printing and explicitly note so on the product page. Eligible download purchases may be exchanged for printed copies in accordance with the TMS Refund Policy.

Can I copy text from a .PDC document?
The Locklizard Software does not allow highlighting or copying of text. However, screenshots are permitted.

Can I access .PDC documents offline?
Documents can be viewed offline, however, the software will require an internet connection once every 7 days to perform a license validity check.

Can I install Locklizard software on a server for multi-user access?
Locklizard cannot be installed on a server and only provides single-user access. Click here for multi-user options.

On how many devices can the Locklizard software be installed?
Licenses from TMS can be activated on up to 2 devices and are for single user access only.

I replaced my computer and need to install the software on my new machine. How can I get more licenses?
Contact TMS if you need additional licenses for your account.


Error Message: No more licenses are available.
You have registered the maximum number of devices. Contact TMS if you need additional licenses for your account.

Error Message: Cannot file DLL file.
The required .dll file may be blocked by your antivirus. Uninstall the Safeguard Viewer and reinstall with your antivirus disabled or add it to your list of trusted programs.

Error Message: Error while unpacking program.
The file was corrupted during download or by your antivirus software, you don’t have Administrator rights, or are using an unsupported OS.

Error message: You don’t have access to this document – no access to document.
Your keystore may be corrupted — remove the keystore and register again. If the error persists, contact TMS to make sure you were given proper access and have the most updated file.

Error Message: Invalid license file. The license you are using does not match your computer details.
Remove the keystore and register again.

For additional errors, consult the Locklizard Knowledge Base

Installing & Registering the Locklizard Viewer

Installation Video Tutorial – under the Secure PDF Viewers section

  • Ensure that you have Administrator rights to install and register the Locklizard software on your computer. Please note that Locklizard licenses from TMS provide single-user access only and cannot be activated on a server for multiple users.
  • Your order confirmation email contains download links for any digital products you ordered (in .PDC file format).
  • When ordering a protected download for the first time, you will also receive another email with the message Locklizard PDF Viewer. This email contains the links needed to download and install the Locklizard software. These files and links can also be found in your TMS Dashboard on the Downloads and Document License tabs.
  • Download the Safeguard PDF Viewer installer for your operating system using one of the green button(s). Note: The instructions on this page apply to Windows operating systems. Additional instructions for other operating systems can be found on the corresponding download page.
  • Run the installer by right-clicking on the program and selecting Run as administrator.
  • Go back to your email or the Document License and click on the Your Name License link to download the license.
  • Open the license file using Locklizard Safeguard – PDF Viewer to register the software on your device. Licenses from TMS can be activated on up to 2 devices.
  • The message below will appear to confirm your registration. You can now access any .PDC file purchased from TMS using the Locklizard Safeguard Viewer.