Should I keep the preferences of unregistered users?

Create a new project thematic blogs. There was a question of storing the interests and preferences of the user before registering with the system.

Option 1. User preferences are accumulated only after registration. Before registration or authorization, the issue of material is formed without taking into account the interests of the user.

Option 2. An unauthorized user looks at some topics, looks at articles of interest, at this time a set of preferences accumulate for his session and an issue is formed in accordance with them. As soon as the user is registered, this set of preferences is finally attached to him. Or, if he passes authorization, in a certain case (personal computer), preferences are added to those already existing in his profile.
')
The second option seems very interesting, but at the same time, relatively inconvenient in terms of implementation. I would like to hear your opinion.