For collectively owned addresses, such as addresses that belong to legal entities, common solution is a multisig (acronym for Multiple Signatures) Wallet. This is basically a smart contract that has multiple owners. Each owner may suggest some transaction to be executed on behalf of the smart contract, but certain number of approvals from other owners is needed to convince smart contract to actually execute the transaction.
Configuration of multisig Wallet, i.e. set of owners and number of approvals required for transactions, may be changed, though each configuration change need to collect enough approvals from current owners.
This way, every employee has its own private key and is responsible for storing it securely, but no employee may on his own perform transactions on behalf of corporate address. As long as employees join corporation or leave, addresses corresponding to their private keys are added or removed from the set of owners of multisig wallet, though address of the wallet stays the same.