UPDATE: The information in this article is about the former lock mechanism and is not available after the MPC update that took place on the 28th of February 2019. The new lock function will not result in any interest but instead enables you to participate in proof of stake mining.
Given the current blocktime of around 34 seconds the minimum deposit period is around 10 days and the longest 517 days.
The deposit reward is subject to active discussions and might change due to rate or blocktime adjustments in the future. You can follow the process by watching the Metaverse Improvement Proposal (MIP) 2.
How to Deposit
To create a deposit on the lightwallet choose it from the menu or click the icon next to the frozen ETP amount.
Next you can choose your deposit period and the amount. It will automatically calculate the profit. On the testnet (which is used for the screenshots) the deposit period are much shorter to enable faster tests.
After a successful deposit you can see the amount of frozen ETP changed on the portfolio page. It can take a moment for your transaction to get added to the Blockchain. To get a list of your active and completed deposits you can select the ETP history from the portfolio page and select the deposits section.
You can follow the links to get detailed information on the transactions. You can also verify that the transaction has been added to the Blockchain.
You can see that the following script is attached to the input of 10 ETP:
[ 0a ] numequalverify dup hash160 [ 0591545d8b0f2d4f03cab8aa3b77a8111cc4263c ] equalverify checksig
This script will not allow the spending of this output unless the period defined by the 1st parameter has been completed. The miner who adds this transaction to a block will generate a transaction that pays the address defined by the 2nd parameter the deposit reward from the coinbase. This is guaranteed by the consensus rules and a block with deposit transactions but no rewards is invalid.