As long as and so long as have similar meanings. They are both used to talk about longer periods of times. Note that as long as and so long as are generally used to refer to future time.

As long as is often used to state conditions. In clauses introduced by as long as, we use a present tense to refer to the future. Future tenses are usually used in the main clauses.

I will not forget that experience as long as I live. (NOT I will not forget that experience as long as I will live.)

She will not forgive you as long as you do not apologize.

You can take my car as long as / so long as you drive carefully.

You can use my computer as long as / so long as you do not delete anything.

She can stay with us as long as she pays for her food and drinks.

Other conjunctions that can be used to express similar ideas are on condition that and provided that. If is also possible in most cases.

You can take my car on condition that you drive carefully.

You can use my computer provided that you do not delete anything.

She can stay with us on condition that she pays for her food and drinks.