Interesting platform and Aerum seems like a great idea with a strong team behind it!
When does the airdrop end?
You can see when a airdrop ends at the top left of the task / bounty on Crowdholding. It will be next to the title. When you leave a comment on the task or share content, it is recorded on your profile. Once the task is expired, our system moves your tokens to your profile. In your profile settings you are able to add your ETH wallet address. Once you do this you will be able to move your tokens from your Crowdholding account to your ETH Wallet.
I hope this answers your questions burundicraze.