After some research and testing I found a way to do this. The fix will work for any installation. Our problem as stated in my original post is that customers receive a CD (128mb) with our installation. We call this the BASE. They install the product at various workstations and servers and move on with their lives. Months later they find a bug and now need to get an update ASAP. Sending a CD is usually time-consuming. So, as soon as we fix the problem we post an update (6MB) on our FTP site. We call this installation INTERIM; its script is very different from the BASE. Our research showed that (1) a license is really a license name + a unique id and (2) installing our INTERIM on top of a registered application was killing the registration and forcing the customer to re-register the application. This is unacceptable to our customer support guidelines. This brings me to the fix and a scheme to have various installation scripts and use the SAME license. 1) Edit the PRIMARY and SECONDARy .ISM files. This assumes that you are basing your license on the one acquired via another installation. Notepad will do just fine. From now one I will refer to PRIMARY to indicate the .ISM file that you used to acquire the license from the Activation Service website. 2) Search for the keyword "ISDRMLicense" in the PRIMARY. Look for the " ISDRMLicense1" line. This will have the license that your PRIMARY is using. If you created multiple licenses via PRIMARY, you will probably see ISDRMLicense2, ISDRMLicense3, ..., etc.. 3) Copy the entire line containing "ISDRMLicense1" text. Keep in mind that if you have other licenses in this .ism file, you will need to pick the right one. Go to the Activation website and look up the license and write down its ID. Come back to the editor and match the ID (next to the license name) in the .ISM line. 4) Go to your SECONDARY .ism file and search for the keyword "ISDRMLicense". Remove all of the ISDRMLicense1, ISDRMLicense2, ..., etc.. Copy the line from the PRIMARY and make sure that the keyword reads "ISDRMLicense1". Save the file and exit. 5) Edit the SECONDARY .ism file with InstallShield. Set the license to the one you paste in step (4). You can repeat step 4 & 5 for other installations and use the same license.
... View more