What is conveyed by the fact that the beast's exercise of authority was allowed?
Revelation 13:5 (ESV)
5And the beast was given a mouth uttering haughty and blasphemous words, and it was allowed to exercise authority for forty-two months.
The fact that authority was allowed (or was given) makes clear that its authority is limited. This limitation is further illustrated by the fact that the beast may exercise its authority for 42 months—and no more.
5 And the beast was given a mouth uttering haughty and blasphemous words, and it was allowed to exercise authority for forty-two months.