I noticed that HarborMaster for the iPad added a rewind feature. They sell rewinds which you can buy for real money. However, I also noticed that you can use some (one?) without purchasing anything.
My question is do I only get to use one free one? Will it recharge after some time? If so, how long does it usually take for it to recharge? Can I ever get more than 1 free one at a time?