i wanna try make it something like that on rexx or jcl.... or u can tell me if i am wrong
I hope you do realize that the Tivoli product probably took THOUSANDS of hours to develop, and IBM has major advantages that you do not -- namely, they build the hardware and the operating system. Our CA products use a memory-resident table established during IPL, our Compuware products use a memory-resident table loaded from a VSAM file, another product has an Assembler macro that encodes the expiration date and must be recompiled into a load module whenever a license renewal occurs, other products provide us a code (completely encrypted so it looks nothing like a date) that is keyed into a TSO screen or used in a batch job, and so forth. There are MANY ways for software vendors to code expiration dates for their products, and it is not likely you're going to be able to find them all out.
In other words, you are wrong and it is almost certainly impossible to write REXX (or JCL, which has to execute a program) to do what you want. Tivoli might be able to do it, but that's IBM - not you.