The Service Fee is a credit fee applied to your earnings when you repost a track. It is not a monetary fee.
Typically, if you earn 4 or more credits from a repost, a 25% fee will be deducted (rounded down).
For example:
If you earn 4 credits from a repost, 1 credit will be deducted as a service fee, meaning your net earnings will be 3 credits per repost.
If you earn 10 credits from a repost, 2 credits will be deducted, meaning your net earnings will be 8 credits per repost.
If you earn fewer than 4 credits per repost, this fee will not affect you.
Why do we do this?
If too many credits enter the system and not enough are removed, the effectiveness of each credit is gradually reduced (similar to inflation in the economy). The effects would include slower campaigns, or campaigns which fail to use most of the credits.
The service fee aims to help us to manage the supply of credits on RepostExchange and increase overall performance for everyone.