Story related and cannot be missed.
There are 5 memories in DNA Sequence 5, 4 of which have optional objectives which completing them during your initial run through will help you with another achievement later on.
Memory 1 - Escape from Debt
- Do not be detected while escorting the senator
Memory 2 - Follow the Money
- Do not be detected and do not touch the ground while tailing the Senator
Memory 3 - When in Rome...
- Arrive at your destination in less than 3 minutes
Memory 4 - In and Out
- Kill the Banker from a bench without being detected
Memory 5 - Paper Trail
- No optional objective
Once you complete memory 5, the achievement should unlock for you.