Intelliwhite question

Hello!
I am wondering if anyone that uses the intelliwhite cool blue pro system knows anything about the product expiration dates? I purchased one long time ago. However, right after I purchased this, I had TMJ as well as other health complications and had to put all of that on hold….for quite some time. I am hoping that soon I will be able to use it – the kit has never been opened – none of it has – all parts have been in the box. Is it ok to try and use this? I was told they expire after one year (which it has been longer than that) Should I try it, not try it – what could happen if it is expired and I try it out, etc? Any help, advice, suggestions etc will be very much appreciated! I thank you for your time and help with this! <3