Another thing to consider is the context. Some words might have specific meanings in a technical context. For example, "license key" should probably stay as is, but maybe "activation key" is an alternative. I need to ensure that the alternatives are contextually appropriate and make sense in the software licensing domain.
For "Use," synonyms could be Utilize, Employ, Apply. "Valid product key" might be Genuine license code, Legitimate activation key, Authorized software token. "Have" could be Possess, Own, Hold. "Use" again here might be Implemented, Applied, Utilized. "Activate" could be Engage, Enable, Switch on. For "instead of using a keygen tool," synonyms for "instead of" are Rather than, In place of, As an alternative to, and "keygen tool" can be cracked license generator, pirated activation program, software unlocker. Autodesk Inventor 2008 Professional Keygen Fix -Xforce-
"Using" becomes Employing.