It works only when your phone/tablet is on charge (50% or more battery minimum availability, changeable via preferences) and connected to wifi, and as such it doesn't use any mobile data and runs when not in use.
I've had it running for the past 72 hours on my Samsung Galaxy S3 and it's now showing up in "my computers" and is adding a few credits. I charge my phone in the evenings so it's running from approx midnight to 7am solid.
As mobile chips are nowhere near as powerful as laptops etc don't expect huge credits.
If nothing else look at is as Tesco...every little helps.
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