Wow. Lots of licensing stuff lately.
This is my usual section for that:
10. ASSIGNMENT AND NON-ASSIGNMENT
If you are an individual and this Agreement is for a single license, then this license is personal to you but you may assign your rights under this Agreement to a third party who agrees in writing to be bound to this Agreement prior to the assignment and provided that you transfer all copies of the Software, registration keys and/or codes, and related documentation to the third party and destroy any copies not transferred. If you are an individual and this Agreement is for a multi-user license, or you are not an individual and are an entity, then you may not assign your rights under this Agreement without the prior written permission of the Company. If you are an entity that merges with or is acquired by another entity then your rights under this Agreement shall be deemed to be temporarily assigned to the resulting entity of that merge or acquisition provided that you supply the Company with written notice not later than the date on which any public announcement of that merger or acquisition is made. Upon receipt of written notice, the Company shall have thirty (30) days to either accept or reject the assignment of rights.
That is very generous compared to most.
The thing is that you need to be fair to people and treat them well. If I buy a book and give it to someone, it's the same thing.
As an author, you need to reserve some rights, but that doesn't mean that you need to treat people badly. Most people are honest. If you can help the honest people stay honest, then that's probably enough. The dishonest ones will figure a way to be dishonest anyways, so why bother? Instead of treating everyone like a thief, you can treat people with respect and hope that they return the favor.