My $1 Re-Usable Starbucks Cup

So I bought a $1 re-usable cup from Starbucks and have used it about 5 times in the past couple weeks. The barista told me that the cup is good for at least 30 coffees but didn't really give me much details.  I mean, does Starbucks assume we handwash our cups?  Did they take into account those who will put it in the dishwasher?  Does it even matter?

I'm going to keep track of each time I use the cup for a coffee (whether I make it or not), other (which includes tea or lemon juice) and each time I put it in the dishwasher.

I'm sure these cups are durable enough to handle 30 hot coffees!!