Hi, I would like to understand the difference between the standard and the Pro license. We need a floating license for running Quartus II 13.1 for Cyclone III and Nios II application. Is Part#: SW-PE-QRTS-FLT applicable for us?

13.1 is now 5 years old, so I'm not sure why you would want to use such old software unless you have some requirement for it. But for any version before 15.1, you would need the Quartus II Subscription edition.

For 15.1 and later, it's the Intel Quartus Prime Standard edition. They're the exact same thing license-wise (annual subscription license). It was just a name change from when Altera was purchased by Intel. The latest version of the software is 18.1.