If you have an Intermittent license, your license key is programmed to allow you to activate multiple licenses. For example, with a 3/12 Intermittent license you can activate three 30-day licenses. You must activate them all within 12 months of your purchase date (they can finish after the anniversary date, but they must start on or before that date). 

Each time you activate a 30-day license, a new file with the extension .lic will be created in the folder C:\ProgramData\Simerics (sometimes if there is a permission issue with that folder they will be in C:\Program Files\Simerics). 

To determine how many 30-day licenses have been used, count the number of *.lic files that have been created since you purchased the Intermittent license. To make this easier, you could consider deleting any files from a previous Intermittent license (for example, if you had a 3/12 Intermittent license, and now have purchased a new 3/12 Intermittent license, you could delete any .lic files that were created during the previous license).

Remember that you don't have to activate a license on the same computer each time. For example, if you have a heavy workload one month, you could activate one of your three Intermittent licenses on one computer, and a second one on a different computer. This consumes two of your three licenses (in the case of a 3/12 Intermittent license), so be sure to count the .lic files on each computer where you have activated a license.