This is the reply I received when asking about how long it took for a purchase to clear:
"It can take from 90 to 120 days for sales to clear.
Please be assured that alamy have a dedicated Credit Control department constantly working on outstanding payments, we pride ourselves on having an outstanding record of recovery. In very few circumstances do we not receive the full amount of the payment."
The image I was questioning has been pending since 12 August. That's 130 days as of today. I'm just hoping the sales I had in November clear a bit faster.