Is there any minimum permanence period in order to receive my rewards?

Rewards are calculated every 30 minutes taking into account the different variables that may change the APY: cryptocurrency in which you receive the reward, natural variation of APY, your Space Center level or Lockup Pool in case you have added Bit2Me Token (B2M).

The rewards generated are delivered on a daily or weekly basis (depending on the chosen reward) and can be withdrawn from the Earn service from the moment they are received, except for those rewards generated through one of the B2M Lockup Pool. These rewards will be credited and added to your balance in the B2M Lockup Pool and will be available to you once the deadlines of each of the Pools are met. For example:

• If I lock today 50.000 B2M in the Lockup Pool for 6 months - During these 6 months I will receive daily rewards that will be added to the locked 50.000 B2M. They will be unlocked when the period of 6 months is over, together with all the rewards generated and will be added to the Flexible B2M Pool. Once unlocked I will be able to withdraw to Wallet in order to sell/exchange or lock them again in order to get a higher APY.
  
  
• If I add today funds to Earn of any cryptocurrency but I set up to receive the rewards in B2M - The generated rewards will be received on a daily basis and they will be credited to Bit2Me Token Flexible Farming Pool (B2M). These rewards will be available and can be withdrawn at any time to wallet in order to sell/exchange, etc.
  
  
• If I add today funds to Earn of any cryptocurrency and set up to receive rewards in the same cryptocurrency - The generated rewards will be received weekly and will be credited to the same wallet of the cryptocurrency added in Earn. These rewards will be available and can be withdrawn at any time to wallet in order to sell/exchange, etc.

This functionality is available for at least 3.17.5. APP version. Lockup option is not available for older app versions.
For more information you can check the following articles:

How often are rewards paid out?

How does Bit2Me Earn work with B2M?