Is keil software for programming microcontrollers a free tool, or does it need to be purchased with a license? Thanks.

Have a look at the primary source: http://www.keil.com/
Of course, all Keil software tools are not freeware (one of the Product page headers: "Why Buy Tools From Keil?").
There are evaluation versions...
Of course, it's the case where "Google is your friend", not DaniWeb...

Is keil software for programming microcontrollers a free tool, or does it need to be purchased with a license? Thanks.

You can download the uVision IDE with an evaluation compiler that's limited to 2K of object code. If it's the c51 compiler you want, that should be good for a couple hundred lines of code.

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