The Enjin Wallet is a Hierarchical Deterministic (HD) Wallet, which means it generates a unique wallet address upon creating your wallet.
To fortify your security and anonymity of your Bitcoin (BTC) and Litecoin (LTC) funds, the Enjin Wallet adopts the common standard of generating a new wallet address after every Bitcoin and Litecoin transaction.
This is a security feature of Bitcoin and Litecoin, not a feature specific to the Enjin Wallet.
While a new address will be generated after each BTC/LTC transaction, you can still send funds to any of your previously generated addresses in the Enjin Wallet.
Your XPUB address allows you to track all of the different BTC/LTC wallet addresses generated and can total your entire balance and transactions across them.
To find your XPUB address, open your BTC or LTC wallet and tap on the three-dot menu located on the top right. Tap "XPUB Address" to display the address.