How do I use the Lifetime Contract item?

Once a unit reaches 100 loyalty, your unit will get a permanent 2% boost to their HP, ATK, DEF, HIT, EVA, and CRIT. You’ll also be able to use a Lifetime Contract on them. Using this on your unit will provide them with the following benefits:

* No loyalty loss

* +20% Bonus EXP

* Exclusive voice

Lifetime Contracts are really hard to come by. You can only purchase them once a month from the Shop and sometimes as event rewards.