I have done a factory reset on my FAS 2020 old system and after that i have lost my FC and ISCSI licences.
Please advise is there anyway i can use this system ?
Er, not really.
If you are the original purchasor, you may be able to recover them by contacting our support center, but they are non-transferrable, so if you aren't, you won't be able to.
If you recover the license codes, it doesn't matter which license goes on which controller - that era of licenses are not locked to a specific serial number.