This is a rare problem: there are three main reasons for it.
The first (and most common) is that the date is set incorrectly on your PC or laptop: check this first!
The second most likely reason is that you have not got the license file into the correct folder. The email which you received from us with the license file will tell you where this is. Use Windows Explorer to look at the contents of this folder, and check that the license file is there. (If you see something like “//10” quoted as your expiry date, this is a good clue that the tutorial can’t find the license file where it should be.)
If the file is in the right folder but you are still getting the error message, the most likely explanation is that you have opened the license file and then ‘saved’ it to the folder. Unfortunately, different email packages and editors work in different ways, and doing this can (in some cases) add characters to the start of the license file. This then throws the software out when it looks through for your license information. Because we don’t know the ins and outs of your email software, we can’t advise you on how to save the attached license file without opening it, but if you consult the help facility you should be able to find the instructions you need. You will be looking for something like “saving attachments” (ie. attached – rather than open – files). We will send you a new license file if you let us know what has happened.
If none of these solve the problem, let us know and we will try to help you sort it out. Please note though, that we cannot teach you to use Windows or your email program over the phone or by email. We will do everything we can, but sometimes the best way forward is to borrow a friendly geek.