Usage of the Software
TRIM Check has no GUI, it runs in a command prompt window. The program is very simple and easy to use. You just copy it on the SSD and run it twice, waiting for at least 30 seconds to a minute between runs in order to ensure accurate results. With most SSDs where TRIM is functional, one minute between runs should suffice.
When executed for the first time, the program will write on specific locations on the SSD. It will then delete the written data and exit.
When you run it for the second time a minute later, it will try to read the exact same locations. If TRIM works you should get zeroes, plus a notification informing you that TRIM is functional.
If the data hasn't been zeroed-out you'll be notified that TRIM is not working or that it hasn't kicked-in yet. In this case I would recommend to wait for at least 10 minutes before running the program for a third time for definite results.
Also note that with some SSDs you may get FF instead of zeroes; this also means that TRIM is alive and doing its job. On the following screenshot I got non-working TRIM. This is an accurate result for my testbed because I also use a certain program that disables TRIM in order to ensure its SSD compatibility.