(available from within your account) with every request as an “Authorization: Bearer” HTTP header.

curl -H "Authorization: Bearer kh43k32jhkjhkjh3k2423kj4h32k4jh32s32423FEWf32eklnewfwkj4h32" \
  https://api.sorryapp.com/v1/hello

Any requests made without this header will be rejected with a 401 Unauthorized error.