You do need to employ copy-protection for your software, but as others have said, make it as hassle-free as possible for your customers. Your aim should be to keep honest customers honest, and not make them go through hoops before they can finally use your software.
I would also advice against spending your time on coming up with your own licensing scheme, instead spend that time focusing on your actual product.
Consider using CryptoLicensing - it provides licensing, copy-protection, activations, machine-locking, trials, and other features.
DISCLAIMER: I work for LogicNP Software, the developer of CryptoLicensing.