Along with the miner, you will receive access to some useful extras (like miner instructions / guide). I recommend taking a glance at them before starting to mine.
Lifetime licenses are meant to be valid as long as the product is available and for sale. You can enjoy your license as I don't have plans to shut this project down.
rogue miner can be used for a variety of crypto currencies as it supports SHA256 and Scrypt mining algorithms. for a detailed list, you can check all supported coins by those algos.
Multiple crypto currencies can be used for purchasing. Personally I recommend LTC at this time to avoid high transaction fees and long confirmation time.
You can use Rogue Miner on as many systems as you wish, there are no limits on this. Clearly, the more computers will run your instance, the higher income you will obtain.
When completing your purchase, only use the addresses generated from checkout page. Trust nobody on discord/telegram claiming to be me and providing you with personal addresses.