Yes, tramadol is habituating and tolerance may develop over time which then would require a higher dose.

Tramadol has to be activated by the liver to its active metabolite and hence there is a delay in action and perception of relief.

http://en.wikipedia.org/wiki/Tramadol

In doses over 400mg or even approaching 400, people may start to have seizures. This drug also affects serotonin levels, and may interact with serotonergic drugs like SSRIs for depression.

A subset of patients do become addicted...meaning seeking more of the drug for subjective "high" effects. At the high doses there can be withdrawal symptoms if stopped quickly. Tapering off is the best method to discontinue.