vBET caches translation results. You can cache it forever so you will not have to pay for same translation again. We do have automatic cache cleaner, but it can be disabled. So vBET works just as you wrote - only when new text appears to translate we ask external providers for translation. Otherwise it is taken from cache. Still vBET do not pre-cache - it means that vBET will do the first translation, when first request to translated page will come. But for each translation only first request will be slower (because of asking 3rd party translation providers), next requests will be handled with cache, so it is acceptable.

If you have any other questions please just ask

Thanks.