Will i loose my l6 license if i upgrade from 5.16 to 6.xx

Will i loose my l6 license if i upgrade from 5.16 to 6.xx and/or is there a specific max version i can upgrade to whilst keeping my license in place. its x86 only software/board.

No.

The licence is lost only if: You remove it on purpose, or you use the disk with another OS, or you ask to format the disk during USB/CD reinstall.

Depends how you have got it. If you did paid for it on Mikrotik official, you will not loose it. If you have used those “trick-s” online, you will loose it.

To be fair i actually have 0 clue.Ive had this system for years sitting in my attic and wanted to try it🤷🏻‍♂️.Even if it is from those “tricks”(which it probably is since my ISP were cheapskates) shouldn’t it be able to keep it if i do a manual update by transfering the files into winbox.I don’t want to mess it up yet until i get my alix board running

A certified trainer who cares to warn someone about keeping cracked MikroTik systems running…
If it were up to me, I’d take your certification away.

There's a difference between warning advice, and simply stating a logical fact, and you know this. Revoking someone's certification because they know about something's that's going on and have researched how it works, is ridiculous. fortunately it's not up to you to moderate certification.. Lol

The answer is: You should not. But … you will never know till you test this.

I would export license for sure as described there: https://wiki.mikrotik.com/wiki/Manual:License
Write down any info ebout license (screenshot) just to be able to prove mikrotik that you hav such a device
Upgrade.
The question is to upgrade via Winbox or start from scratch with netinstall?

Just do a full disk image backup before upgrading. That way you can always go back to old version if upgrade doesn’t work.
License is bound to the disk drive, but as long as you have the original disk image, it will stay the same after you write it back from backup.