My membership was purchased just x days ago, I was told that they would release rewards for 600 days??

Please understand that unilevel rewards (i.e. rewards you get from having downlines) are released from your existing packages.

For example, if you have a 1000 HU package, you will have a total pending rewards of 3000 HU. If you get 1 HU from your downline, the 1 HU is released from your total pending rewards of 3000 HU.

It does not take 600 days for your memberships to expire if you have HyperDrive rewards.