If a person moves in even for a few days, that person becomes an occupant. If you want to abide by the terms of the lease, follow the notice to landlord provisions about how to trigger approval for "another person". Without reading your particular lease language, it is impossible to say what your remedy might be.
PS - "compensation" is not always the right word to use. Usually there is some "valuable consideration" for any kind of shared living arrangement, and if not it may be a "gift" arrangement, but if this doesn't work out we see altogether too many situations where one person is stuck for all the rent in a situation where one has moved out. Unless you are marrying this fellow the day you move in, you may want to consider either controlling the lease (you may still have to formally evict him if things go south) or getting him on the lease (where you risk having no formal arrangement with him for rent or risking losing control of the lease and the apartment). LIfe is about risks; decide what is more important and I hope things work out for you.
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