The MicroLogix 1200 is supported by RSLogix 500 Micro, Starter, Standard, and Professional editions.
MicroLogix 1200 is not supported by RSLogix 500 Micro Lite, which is the free edition.
As Clay B. mentioned, the lowest-cost option for programming this controller is RSLogix 500 Micro, which is list price $129 USD. The part number is 9324-RLM0100ENE.
If you are going to be programming and supporting a large variety of MicroLogix and SLC-500 controllers, I recommend the RSLogix 500 Standard software. If you just need to program this one MicroLogix 1200, go ahead and use RSLogix 500 Micro.