I cannot find what my current license serial number is to input into the upgraded 2018 FME Server license area. the temporary works for 7 days but want to use the license i had for 2015 server on 2018 server,

I cannot find what my current license serial number is to input into the upgraded 2018 FME Server license area. the temporary works for 7 days but want to use the license i had for 2015 server on 2018 server,
