I have a blood red cleaner shrimp that I have had for 6 years. I put him in my very first 12 gallon aquapod, and now he is in Megan's Elos Mini. He has been in a 12 gallon aquapod, 100 gallon reef, 39 gallon reef and now resides in the Elos Mini.
I always heard they max out at about 3 years, but mine has easily doubled that.
~Michael