one user

Hi,
We have a one user licence for a pdf software.
I would like to create a web page which only allows one user at a time to open a .pdf file
I guess I have to program this into the page. For example user one opens the .pdf file and then a sql server table is updated. Then a second user can not open the .pdf file because there is a value in the table. And when the first user finishes with the .pdf then the second user can open it.

What do you think please?
Thanks

That's not possible. You have no way of tracking whether the PDF was closed, saved, or opened. Second, the nature of the web is such that it's stateless, meaning that 1000 users can come over and download that PDF file.

I think you might have misunderstood the clause "one user license for a pdf software." It must be for USING that software, not for using the PDF that it creates.