I would memorize those that I want to keep in my repertoire. Those that I am just playing to practice my technique or to learn new things, I would follow the tab or sheet music.

Licks I try to memorize so I can improv to other songs by repeating or just changing it a little to fit the groove. Progressions, I just follow the tab unless I intend to play it a lot or with someone else.

Just my 2 cents.

I'm new to guitar tricks, just got a year membership, but I like it so far. A lot of info. packed in here. There is no way to memrize it all.:)