Blake smokes marijuana. when he first started using, he used to get high off one joint, but now he finds he needs to smoke more and more to get the same high. this is an example of

Based o on the description, this is an example of tolerance

Whenever we inject a new substance to our body, our cells will adapt to its existence around them, which cause us to feel less and less effective because of it over time.
In this case, Blake could only achieve the same effect like he used to the first time only if he increases the dosage.