That's great feedback -- we're still working on the best way to do pricing. A phrase is any text wrapped with our 'tr' function. We use phrases for pricing currently because it's an industry norm but we're open to changing it if it causes confusion.
I think the confusion for me was that there is also a pay-per-word price; then for me the limit on the number of phrases does not feel logical. Phrases as tr() calls for me as a developer also depend quite a bit on how I have setup the translation and differ per project.
I would expect to pay a monthly fee for the online service + a fee for each word. Also, 100 unique tr()'s seem a bit limiting? (even smaller projects for me quickly get > 1000 separate tr calls)