Have a licensed 2.5.4, tested 2.6.1, now old version unlicensed

I'm working at a company that uses AW 2.5.4, which is many years old now. I dropped in the trial of 2.6.1 to test it out and now even when I put 2.5.4 back in I'm getting the unlicensed message in red over my grid.

How can I fix this?

Any help? been a month...